.aliases: Add `gem cleanup` to `update` alias
.aliases: Add `gem cleanup` to `update` alias

This ensure that old gems are removed after `gem update`.

Closes #705.

acourtneybrown/dotfiles,smnorris/dotfiles,tomfuertes/dotfiles,MikeGoldsmith/dotfiles,wmccarthy/dotfiles,shabith/dotfiles,serv/dotfiles-1,quimrstorres/dotfiles,ryan-w-moore/dotfiles,anmolnagpal/dotfiles,lucafavatella/mathiasbynens-dotfiles,beausmith/dotfiles,zarth/dotfiles,KoltonA/dotfiles,clawfire/dotfiles,micck/dotfiles,vocino/dotfiles,unity/dotfiles,andreimc/dotfiles,evansenter/dotfiles,do0g/dotfiles,drewhunter/dotfiles,VikramTiwari/dotfiles-mathias,anonymint/dotfiles,rylectro/dotfiles,loujiayu/dotfiles,ncoelle/dotfiles_mathiasbynens,timshadel/dotfiles,wiki05/dotfiles,allwinpb/dotfiles,jfridye/dotfiles,fbcotter/dotfiles,cappadona/dotfiles,blazvi/dotfiles,unity/dotfiles,wmccarthy/dotfiles,iblamefish/dotfiles,mrkd/dotfiles,yangsu/dotfiles,tallboy/dotfiles,trymbill/dotfiles,anup-ap/dotfiles,shanez/dotfiles,ajliv/dotfiles,margaritis/dotfiles,jeffbyrnes/dotfiles,mathiasbynens/dotfiles,jmuth/dotfiles,johnbuffington/dotfiles,imattman/dotfiles-mathiasbynens,tornqvist/dotfiles,xcompass/dotfiles,colingourlay/dotfiles,rowleyaj/dotfiles,tarpdalton/dotfiles,vitaligent/dotfiles,theanxy/dotfiles,dmnsgn/dotfiles,boennemann/dotfiles,ironprogrammer/dotfiles,joshes/dotfiles,deffjay/dotfiles,christianv/dotfiles,dincho/dotfiles,cemo/dotfiles,DavidPrichard/dotfiles,mattsearles/dotfiles,fThues/dotfiles,WooD1k/dotfiles,pdeffendol/dotfiles,yutianqiuhao/dotfiles,wmccarthy/dotfiles,laserson/dotfiles,henryhadlow/dotfiles,snuzinator/dotfiles-1,jcloutz/dotfiles,bustardcelly/dotfiles,satie/dotfiles,malash/dotfiles,BigGillyStyle/dotfiles-lw,lipis/dotfiles,mserranom/dotfiles,alexdiliberto/dotfiles,auzwang/dotfiles,satie/dotfiles,michaelsharpe/dotfiles,jeffbyrnes/dotfiles,kunsang/dotfiles,pdeffendol/dotfiles,deffjay/dotfiles,olistic/dotfiles,coreyja/dotfiles,VikramTiwari/dotfiles-mathias,LambertoD/dotfiles,tallboy/dotfiles,enavarrocu/dotfiles,miguelff/dotfiles,FradSer/dotfiles,dodeja/dotfiles,alexdiliberto/dotfiles,mhausmann/dotfiles,miguelff/dotfiles,theneonlobster/dotfiles,samwize/dotfiles,thrasher/dotfiles,alexdiliberto/dotfiles,margaritis/dotfiles,poommooq/dotfiles,nodemaker/dotfiles,leoapost/dotfiles,vesparny/dotfiles,mosleywm/dotfiles,vitorhsb/dotfiles,imattman/dotfiles-mathiasbynens,tornqvist/dotfiles,thinktwo/dotfiles,chriswoodley/dotfiles,jfroffice/dotfiles,khsing/dotfiles,timshadel/dotfiles,snuzinator/dotfiles-1,jannyg/dotfiles,AlexanderNZ/dotfiles,asbjornu/dotfiles,ncoelle/dotfiles_mathiasbynens,heitorPB/dotfiles,kevinhwang/dotfiles,jfitzsimmons2/dotfiles,podruh/dotfiles,felics/dotfiles,dodeja/dotfiles,chao-xian/dotfiles,ryan-w-moore/dotfiles,jorvi/dotfiles,michaelx/dotfiles,nitr8/dotfiles,jleajones/dotfiles,mike1e/dotfiles,coinsk/dotfiles,c05mic/dotfiles,christianvuerings/dotfiles,LimoWanKenobi/dotfiles,CsupiUK/dotfiles,adrianforsius/dotfiles-1,fredriksundstrom/dotfiles,yahyavi/dotfiles,adrianforsius/dotfiles-1,vitaligent/dotfiles,varunyellina/dotfiles,shabith/dotfiles,nicksen/osx_dotfiles,nowucca/dotfiles,EvanWillms/dotfiles,DylanVann/dotfiles,hadees/dotfiles,laurent-le-graverend/dotfiles-osx,timyardley/dotfiles,dgrebb/dotfiles,davehouse/dotfiles,henninghoyer/dotfiles,XanderDwyl/dotfiles,waja/dotfiles,mp3sii/dotfiles,svassr/dotfiles,mikegreiling/dotfiles,adriantofan/dotfiles,snuzinator/dotfiles-1,jfroffice/dotfiles,christianv/dotfiles,jmillerdesign/dotfiles,vboiteau/dotfiles,blazvi/dotfiles,varunyellina/dotfiles,nilshartmann/dotfiles,remitbri/dotfiles,colingourlay/dotfiles,unity/dotfiles,michalsanger/dotfiles,gully/dotfiles,tallboy/dotfiles,unity/dotfiles,cappadona/dotfiles,AlexanderNZ/dotfiles,triq6/dotfiles,kunsang/dotfiles,fabian/dotfiles,timmywil/dotfiles,christianvuerings/dotfiles,alimony/dotfiles,JustinTullgren/dotfiles,chosenken/dotfiles,willbowditch/dotfiles,wiki05/dotfiles,quimrstorres/dotfiles,christianv/dotfiles,anonymint/dotfiles,vboiteau/dotfiles,topless/dotfiles,whisperoh/dotfiles,WooD1k/dotfiles,eupestov/dotfiles,tonioriol/dotfiles,michaelsharpe/dotfiles,jcloutz/dotfiles,kevinhwang/dotfiles,Quantisan/dotfiles,mvayngrib/dotfiles,Danny02/dotfiles,ctesniere/dotfiles-1,teloon/dotfiles,mnkhouri/mathiasbynens,theand/mathiasdotfiles,ly-nx/dotfiles,developdaly/dotfiles,hadibadjian/dotfiles,JeroenVdb/dotfiles,brwnj/dotfiles,LambertoD/dotfiles,gregpoulos/dotfiles,miku/dotfiles,coreyja/dotfiles,jcloutz/dotfiles,jooray/dotfiles,LimoWanKenobi/dotfiles,hadees/dotfiles,atancasis/dotfiles,jawee/dotfiles,rylectro/dotfiles,thinktwo/dotfiles,vitorhsb/dotfiles,wickles/dotfiles,mdjnewman/dotfiles,vocino/dotfiles,Jeddf/dotfiles,khsing/dotfiles,BradMcGonigle/dotfiles,rahulsom/dotfiles,Tag0Mag0/dotfiles,theand/mathiasdotfiles,yahyavi/dotfiles,triq6/dotfiles,davehouse/dotfiles,Igor1201/dotfiles,mklaber/dotfiles,vesparny/dotfiles,mhoonjeon/dotfiles,jmccarrell/dotfiles,mohuk/dotfiles,Julyyq/dotfiles,reuski/dotfiles,todd64/dotfiles,ahmadassaf/dotfiles,blazvi/dotfiles,BradMcGonigle/dotfiles,picturae/dotfiles,ryanfreeth/dotfiles,aceoliver/dotfiles,jklmnop/dotfiles,zangrafx/dotfiles,ssanchez/dotfiles,alimony/dotfiles,trymbill/dotfiles,hulkish/dotfiles,evansenter/dotfiles,mdjnewman/dotfiles,miku/dotfiles,johndryan/dotfiles,miku/dotfiles,vesparny/dotfiles,BigGillyStyle/dotfiles-lw,gully/dotfiles,dodeja/dotfiles,mikaelengstrom/dotfiles,brwnj/dotfiles,Jeddf/dotfiles,PStrakendal/dotfiles,whisperoh/dotfiles,carlosliu/dotfiles,difujia/dotfiles,poommooq/dotfiles,wmccarthy/dotfiles,SamirBoulil/dotfiles,ryancat/dotfiles,jmccarrell/dotfiles,jeffbyrnes/dotfiles,olistic/dotfiles,hcavillones/dotfiles,jooray/dotfiles,rtfpessoa/dotfiles,olistic/dotfiles,twinch/dotfiles,kevinhwang/dotfiles,MrMaksimize/dotfiles,ianvanness/dotfiles,jacktonkin/dotfiles,micck/perv-dotfiles,mlefoster/dotfiles,carlosliu/dotfiles,nicksen/osx_dotfiles,bwaibel/dotfiles,smuldr/dotfiles,bwaibel/dotfiles,clawfire/dotfiles,tallboy/dotfiles,Danny02/dotfiles,dodeja/dotfiles,bplommer/dotfiles,mrkd/dotfiles,wmccarthy/dotfiles,snuzinator/dotfiles-1,ssanchez/dotfiles,atancasis/dotfiles,mrjefftang/dotfiles,wmccarthy/dotfiles,vanev/dotfiles,ajordens/dotfiles,coreyja/dotfiles,reuski/dotfiles,nub4life/dotfiles,fThues/dotfiles