Fix slug create and update logic for posts
Fix slug create and update logic for posts

-Remove unnecessary calls to the slug API endpoint on the
 content screen.
-Only make slug API endpoint calls in editor when the post is new.
-Improve logic for when to update the slug.

mtvillwock/Ghost,ryanbrunner/crafters,jamesslock/Ghost,ghostchina/Ghost-zh,edurangel/Ghost,edurangel/Ghost,camilodelvasto/herokughost,etanxing/Ghost,zackslash/Ghost,daimaqiao/Ghost-Bridge,mnitchie/Ghost,kolorahl/Ghost,DesenTao/Ghost,adam-paterson/blog,axross/ghost,dqj/Ghost,augbog/Ghost,Alxandr/Blog,JohnONolan/Ghost,javorszky/Ghost,acburdine/Ghost,francisco-filho/Ghost,scopevale/wethepeopleweb.org,mlabieniec/ghost-env,ManRueda/manrueda-blog,Xibao-Lv/Ghost,carlosmtx/Ghost,ignasbernotas/nullifer,bisoe/Ghost,mohanambati/Ghost,achimos/ghost_as,codeincarnate/Ghost,zeropaper/Ghost,mattchupp/blog,allanjsx/Ghost,developer-prosenjit/Ghost,lowkeyfred/Ghost,jparyani/GhostSS,trunk-studio/Ghost,omaracrystal/Ghost,jomahoney/Ghost,pollbox/ghostblog,yangli1990/Ghost,vainglori0us/urban-fortnight,AlexKVal/Ghost,jiachenning/Ghost,Shauky/Ghost,ljhsai/Ghost,UnbounDev/Ghost,ClarkGH/Ghost,dylanchernick/ghostblog,ManRueda/manrueda-blog,bitjson/Ghost,ITJesse/Ghost-zh,rchrd2/Ghost,telco2011/Ghost,sunh3/Ghost,mdbw/ghost,dymx101/Ghost,lf2941270/Ghost,Trendy/Ghost,lanffy/Ghost,TribeMedia/Ghost,BlueHatbRit/Ghost,bbmepic/Ghost,vishnuharidas/Ghost,sifatsultan/js-ghost,Azzurrio/Ghost,hnq90/Ghost,carlyledavis/Ghost,andrewconnell/Ghost,Jai-Chaudhary/Ghost,dggr/Ghost-sr,llv22/Ghost,sebgie/Ghost,load11/ghost,telco2011/Ghost,nmukh/Ghost,ErisDS/Ghost,JonathanZWhite/Ghost,mikecastro26/ghost-custom,epicmiller/pages,schneidmaster/theventriloquist.us,Yarov/yarov,TryGhost/Ghost,neynah/GhostSS,gleneivey/Ghost,tyrikio/Ghost,cncodog/Ghost-zh-codog,krahman/Ghost,janvt/Ghost,mttschltz/ghostblog,Azzurrio/Ghost,kmeurer/Ghost,jgillich/Ghost,ananthhh/Ghost,carlyledavis/Ghost,jaguerra/Ghost,ashishapy/ghostpy,neynah/GhostSS,sebgie/Ghost,Alxandr/Blog,rizkyario/Ghost,devleague/uber-hackathon,etanxing/Ghost,STANAPO/Ghost,flomotlik/Ghost,wspandihai/Ghost,bisoe/Ghost,schneidmaster/theventriloquist.us,jeonghwan-kim/Ghost,karmakaze/Ghost,bosung90/Ghost,imjerrybao/Ghost,ballPointPenguin/Ghost,jacostag/Ghost,Japh/shortcoffee,rito/Ghost,pathayes/FoodBlog,pensierinmusica/Ghost,jparyani/GhostSS,novaugust/Ghost,ericbenson/GhostAzureSetup,bbmepic/Ghost,jorgegilmoreira/ghost,dbalders/Ghost,GarrethDottin/Habits-Design,singular78/Ghost,vainglori0us/urban-fortnight,imjerrybao/Ghost,manishchhabra/Ghost,hoxoa/Ghost,JohnONolan/Ghost,francisco-filho/Ghost,hilerchyn/Ghost,GroupxDev/javaPress,codeincarnate/Ghost,barbastan/Ghost,stridespace/Ghost,epicmiller/pages,anijap/PhotoGhost,sunh3/Ghost,Elektro1776/javaPress,diancloud/Ghost,laispace/laiblog,aroneiermann/GhostJade,kevinansfield/Ghost,tuan/Ghost,InnoD-WebTier/hardboiled_ghost,kaychaks/kaushikc.org,fredeerock/atlabghost,Kikobeats/Ghost,vloom/blog,devleague/uber-hackathon,floofydoug/Ghost,panezhang/Ghost,ashishapy/ghostpy,KnowLoading/Ghost,obsoleted/Ghost,GarrethDottin/Habits-Design,letsjustfixit/Ghost,nneko/Ghost,flpms/ghost-ad,sebgie/Ghost,patterncoder/patterncoder,RufusMbugua/TheoryOfACoder,woodyrew/Ghost,k2byew/Ghost,cwonrails/Ghost,dymx101/Ghost,Gargol/Ghost,melissaroman/ghost-blog,uploadcare/uploadcare-ghost-demo,ygbhf/Ghost,sfpgmr/Ghost,ryansukale/ux.ryansukale.com,mnitchie/Ghost,hnq90/Ghost,pbevin/Ghost,AlexKVal/Ghost,shannonshsu/Ghost,dggr/Ghost-sr,IbrahimAmin/Ghost,ClarkGH/Ghost,memezilla/Ghost,chris-yoon90/Ghost,qdk0901/Ghost,denzelwamburu/denzel.xyz,kwangkim/Ghost,r14r/fork_nodejs_ghost,Kikobeats/Ghost,wallmarkets/Ghost,daimaqiao/Ghost-Bridge,PDXIII/Ghost-FormMailer,olsio/Ghost,greyhwndz/Ghost,kolorahl/Ghost,adam-paterson/blog,v3rt1go/Ghost,r14r/fork_nodejs_ghost,yundt/seisenpenji,MrMaksimize/sdg1,dbalders/Ghost,praveenscience/Ghost,phillipalexander/Ghost,klinker-apps/ghost,mayconxhh/Ghost,lukw00/Ghost,Feitianyuan/Ghost,hnarayanan/narayanan.co,darvelo/Ghost,davidenq/Ghost-Blog,Kaenn/Ghost,rito/Ghost,ThorstenHans/Ghost,AnthonyCorrado/Ghost,pedroha/Ghost,gabfssilva/Ghost,javimolla/Ghost,hyokosdeveloper/Ghost,skleung/blog,jiangjian-zh/Ghost,YY030913/Ghost,ckousik/Ghost,yangli1990/Ghost,Alxandr/Blog,zackslash/Ghost,johngeorgewright/blog.j-g-w.info,akveo/akveo-blog,Japh/Ghost,greyhwndz/Ghost,Elektro1776/javaPress,icowan/Ghost,aschmoe/jesse-ghost-app,dai-shi/Ghost,rmoorman/Ghost,johngeorgewright/blog.j-g-w.info,jomofrodo/ccb-ghost,beautyOfProgram/Ghost,tadityar/Ghost,johnnymitch/Ghost,e10/Ghost,Dnlyc/Ghost,developer-prosenjit/Ghost,sceltoas/Ghost,e10/Ghost,TribeMedia/Ghost,anijap/PhotoGhost,laispace/laiblog,javimolla/Ghost,dgem/Ghost,tksander/Ghost,netputer/Ghost,notno/Ghost,akveo/akveo-blog,diogogmt/Ghost,tidyui/Ghost,vainglori0us/urban-fortnight,wemakeweb/Ghost,kwangkim/Ghost,sajmoon/Ghost,netputer/Ghost,atandon/Ghost,lanffy/Ghost,daimaqiao/Ghost-Bridge,lethalbrains/Ghost,gcamana/Ghost,thehogfather/Ghost,pbevin/Ghost,cicorias/Ghost,madole/diverse-learners,velimir0xff/Ghost,ananthhh/Ghost,TryGhost/Ghost,DesenTao/Ghost,GroupxDev/javaPress,SachaG/bjjbot-blog,Japh/Ghost,ThorstenHans/Ghost,tmp-reg/Ghost,darvelo/Ghost,Sebastian1011/Ghost,javorszky/Ghost,r1N0Xmk2/Ghost,yanntech/Ghost,lukekhamilton/Ghost,Elektro1776/javaPress,jparyani/GhostSS,pathayes/FoodBlog,cncodog/Ghost-zh-codog,sceltoas/Ghost,flpms/ghost-ad,ivanoats/ivanstorck.com,Brunation11/Ghost,fredeerock/atlabghost,Aaron1992/Ghost,Remchi/Ghost,SachaG/bjjbot-blog,rafaelstz/Ghost,lf2941270/Ghost,Romdeau/Ghost,NovaDevelopGroup/Academy,tksander/Ghost,metadevfoundation/Ghost,Bunk/Ghost,veyo-care/Ghost,hyokosdeveloper/Ghost,ErisDS/Ghost,Trendy/Ghost,letsjustfixit/Ghost,InnoD-WebTier/hardboiled_ghost,jaswilli/Ghost,wemakeweb/Ghost,zhiyishou/Ghost,thehogfather/Ghost,katrotz/blog.katrotz.space,PaulBGD/Ghost-Plus,cysys/ghost-openshift,diancloud/Ghost,situkangsayur/Ghost,InnoD-WebTier/hardboiled_ghost,jiachenning/Ghost,FredericBernardo/Ghost,woodyrew/Ghost,rollokb/Ghost,UsmanJ/Ghost,Smile42RU/Ghost,RufusMbugua/TheoryOfACoder,SkynetInc/steam,sangcu/Ghost,alecho/Ghost,etdev/blog,etdev/blog,Smile42RU/Ghost,tadityar/Ghost,handcode7/Ghost,omaracrystal/Ghost,blankmaker/Ghost,no1lov3sme/Ghost,weareleka/blog,disordinary/Ghost,alecho/Ghost,rameshponnada/Ghost,flomotlik/Ghost,ryanbrunner/crafters,letsjustfixit/Ghost,lcamacho/Ghost,tidyui/Ghost,daihuaye/Ghost,davidmenger/nodejsfan,kaiqigong/Ghost,aroneiermann/GhostJade,dai-shi/Ghost,theonlypat/Ghost,duyetdev/islab,achimos/ghost_as,SkynetInc/steam,lukaszklis/Ghost,claudiordgz/Ghost,virtuallyearthed/Ghost,pensierinmusica/Ghost,hoxoa/Ghost,kortemy/Ghost,Coding-House/Ghost,r1N0Xmk2/Ghost,ivantedja/ghost,melissaroman/ghost-blog,bsansouci/Ghost,ineitzke/Ghost,karmakaze/Ghost,schematical/Ghost,yundt/seisenpenji,telco2011/Ghost,nneko/Ghost,allanjsx/Ghost,syaiful6/Ghost,Gargol/Ghost,dggr/Ghost-sr,jaswilli/Ghost,riyadhalnur/Ghost,cwonrails/Ghost,JonSmith/Ghost,sfpgmr/Ghost,llv22/Ghost,shrimpy/Ghost,jacostag/Ghost,singular78/Ghost,kortemy/Ghost,dYale/blog,freele/ghost,optikalefx/Ghost,Rovak/Ghost,ManRueda/Ghost,claudiordgz/Ghost,ASwitlyk/Ghost,NamedGod/Ghost,janvt/Ghost,andrewconnell/Ghost,Yarov/yarov,katiefenn/Ghost,rizkyario/Ghost,alexandrachifor/Ghost,jomahoney/Ghost,praveenscience/Ghost,BlueHatbRit/Ghost,yanntech/Ghost,Brunation11/Ghost,tchapi/igneet-blog,allspiritseve/mindlikewater,Klaudit/Ghost,bastianbin/Ghost,morficus/Ghost,memezilla/Ghost,ignasbernotas/nullifer,edsadr/Ghost,Kaenn/Ghost,stridespace/Ghost,acburdine/Ghost,BayPhillips/Ghost,virtuallyearthed/Ghost,patterncoder/patterncoder,mayconxhh/Ghost,sangcu/Ghost,UsmanJ/Ghost,gcamana/Ghost,panezhang/Ghost,ManRueda/Ghost,dYale/blog,gleneivey/Ghost,thomasalrin/Ghost,JulienBrks/Ghost,uniqname/everydaydelicious,obsoleted/Ghost,camilodelvasto/localghost,rizkyario/Ghost,dqj/Ghost,NodeJSBarenko/Ghost,Kikobeats/Ghost,JulienBrks/Ghost,jorgegilmoreira/ghost,eduardojmatos/eduardomatos.me,handcode7/Ghost,vloom/blog,axross/ghost,camilodelvasto/herokughost,aschmoe/jesse-ghost-app,ASwitlyk/Ghost,Kaenn/Ghost,jorgegilmoreira/ghost,icowan/Ghost,wallmarkets/Ghost,NovaDevelopGroup/Academy,julianromera/Ghost,liftup/ghost,veyo-care/Ghost,Loyalsoldier/Ghost,optikalefx/Ghost,jeonghwan-kim/Ghost,hnarayanan/narayanan.co,LeandroNascimento/Ghost,MadeOnMars/Ghost,STANAPO/Ghost,Netazoic/bad-gateway,zumobi/Ghost,petersucks/blog,wspandihai/Ghost,IbrahimAmin/Ghost,skleung/blog,Feitianyuan/Ghost,FredericBernardo/Ghost,rouanw/Ghost,rollokb/Ghost,ITJesse/Ghost-zh,thinq4yourself/Unmistakable-Blog,ballPointPenguin/Ghost,theonlypat/Ghost,rameshponnada/Ghost,tandrewnichols/ghost,leonli/ghost,mdbw/ghost,greenboxindonesia/Ghost,chevex/undoctrinate,PDXIII/Ghost-FormMailer,mlabieniec/ghost-env,ghostchina/website,ivanoats/ivanstorck.com,madole/diverse-learners,ErisDS/Ghost,AnthonyCorrado/Ghost,barbastan/Ghost,novaugust/Ghost,zumobi/Ghost,dgem/Ghost,TryGhost/Ghost,Netazoic/bad-gateway,kevinansfield/Ghost,tanbo800/Ghost,Bunk/Ghost,sergeylukin/Ghost,skmezanul/Ghost,delgermurun/Ghost,kmeurer/GhostAzureSetup,Rovak/Ghost,neynah/GhostSS,xiongjungit/Ghost,greenboxindonesia/Ghost,ljhsai/Ghost,mohanambati/Ghost,cobbspur/Ghost,Jai-Chaudhary/Ghost,katrotz/blog.katrotz.space,davidmenger/nodejsfan,Klaudit/Ghost,smedrano/Ghost,hilerchyn/Ghost,ckousik/Ghost,lukaszklis/Ghost,jiangjian-zh/Ghost,Netazoic/bad-gateway,julianromera/Ghost,lukekhamilton/Ghost,daihuaye/Ghost,shrimpy/Ghost,mattchupp/blog,smaty1/Ghost,mttschltz/ghostblog,VillainyStudios/Ghost,bastianbin/Ghost,zhiyishou/Ghost,trepafi/ghost-base,schematical/Ghost,mhhf/ghost-latex,GroupxDev/javaPress,lowkeyfred/Ghost,ManRueda/manrueda-blog,beautyOfProgram/Ghost,jaguerra/Ghost,dylanchernick/ghostblog,Dnlyc/Ghost,metadevfoundation/Ghost,velimir0xff/Ghost,syaiful6/Ghost,psychobunny/Ghost,ghostchina/Ghost-zh,makapen/Ghost,influitive/crafters,mohanambati/Ghost,lethalbrains/Ghost,davidenq/Ghost-Blog,ghostchina/Ghost.zh,wangjun/Ghost,novaugust/Ghost,wangjun/Ghost,bosung90/Ghost,liftup/ghost,jamesslock/Ghost,load11/ghost,PeterCxy/Ghost,k2byew/Ghost,nakamuraapp/new-ghost,PepijnSenders/whatsontheotherside,bsansouci/Ghost,rchrd2/Ghost,ghostchina/Ghost.zh,makapen/Ghost,PepijnSenders/whatsontheotherside,exsodus3249/Ghost,chris-yoon90/Ghost,leonli/ghost,influitive/crafters,xiongjungit/Ghost,pedroha/Ghost,skmezanul/Ghost,atandon/Ghost,JohnONolan/Ghost,prosenjit-itobuz/Ghost,Japh/shortcoffee,NikolaiIvanov/Ghost,AileenCGN/Ghost,kmeurer/Ghost,JonathanZWhite/Ghost,augbog/Ghost,delgermurun/Ghost,olsio/Ghost,JonSmith/Ghost,jomofrodo/ccb-ghost,disordinary/Ghost,zeropaper/Ghost,thomasalrin/Ghost,ddeveloperr/Ghost,patrickdbakke/ghost-spa,jgillich/Ghost,duyetdev/islab,Remchi/Ghost,sankumsek/Ghost-ashram,weareleka/blog,UnbounDev/Ghost,tmp-reg/Ghost,gabfssilva/Ghost,singular78/Ghost,sajmoon/Ghost,cncodog/Ghost-zh-codog,arvidsvensson/Ghost,qdk0901/Ghost,ngosinafrica/SiteForNGOs,Loyalsoldier/Ghost,pollbox/ghostblog,KnowLoading/Ghost,kortemy/Ghost,floofydoug/Ghost,kevinansfield/Ghost,uploadcare/uploadcare-ghost-demo,carlosmtx/Ghost,cwonrails/Ghost,kaychaks/kaushikc.org,PaulBGD/Ghost-Plus,ryansukale/ux.ryansukale.com,laispace/laiblog,prosenjit-itobuz/Ghost,stridespace/Ghost,NikolaiIvanov/Ghost,rmoorman/Ghost,djensen47/Ghost,leonli/ghost,allspiritseve/mindlikewater,johnnymitch/Ghost,ericbenson/GhostAzureSetup,jin/Ghost,benstoltz/Ghost,devleague/uber-hackathon,morficus/Ghost,denzelwamburu/denzel.xyz,benstoltz/Ghost,jgladch/taskworksource,tandrewnichols/ghost,sergeylukin/Ghost,mtvillwock/Ghost,aexmachina/blog-old,psychobunny/Ghost,lukw00/Ghost,sifatsultan/js-ghost,mhhf/ghost-latex,v3rt1go/Ghost,Polyrhythm/dolce,ladislas/ghost,trunk-studio/Ghost,camilodelvasto/localghost,ngosinafrica/SiteForNGOs,Coding-House/Ghost,cysys/ghost-openshift,ManRueda/Ghost,davidenq/Ghost-Blog,NamedGod/Ghost,klinker-apps/ghost,jomofrodo/ccb-ghost,exsodus3249/Ghost,ineitzke/Ghost,thinq4yourself/Unmistakable-Blog,situkangsayur/Ghost,acburdine/Ghost,ygbhf/Ghost,cysys/ghost-openshift,rouanw/Ghost,blankmaker/Ghost,smedrano/Ghost,BayPhillips/Ghost,leninhasda/Ghost,PeterCxy/Ghost,RoopaS/demo-intern,VillainyStudios/Ghost,ddeveloperr/Ghost,bitjson/Ghost,kaiqigong/Ghost,tanbo800/Ghost,edsadr/Ghost,bigertech/Ghost,diogogmt/Ghost,LeandroNascimento/Ghost,YY030913/Ghost,cicorias/Ghost,nmukh/Ghost,no1lov3sme/Ghost,petersucks/blog,tyrikio/Ghost,cqricky/Ghost,djensen47/Ghost,NovaDevelopGroup/Academy,MadeOnMars/Ghost,mlabieniec/ghost-env,leninhasda/Ghost,notno/Ghost,jin/Ghost,ladislas/ghost,choskim/ghost_exp,phillipalexander/Ghost,dbalders/Ghost,rafaelstz/Ghost,smaty1/Ghost,Netazoic/bad-gateway,riyadhalnur/Ghost,shannonshsu/Ghost,cqricky/Ghost,manishchhabra/Ghost,Sebastian1011/Ghost,allanjsx/Ghost,Romdeau/Ghost,arvidsvensson/Ghost,Xibao-Lv/Ghost