Fix Adjustment#order= issue for non-order items
Fix Adjustment#order= issue for non-order items

If you attempt to assign a non-order to this association, then it gives you a cryptic 'uninitialized constant Order' error. No fun at all! By specifying the class name, it'll show you the right error.

Related to #3856

APohio/spree,RatioClothing/spree,forkata/solidus,softr8/spree,rbngzlv/spree,nooysters/spree,FadliKun/spree,rakibulislam/spree,mleglise/spree,mleglise/spree,net2b/spree,pulkit21/spree,vmatekole/spree,richardnuno/solidus,surfdome/spree,omarsar/spree,NerdsvilleCEO/spree,vinayvinsol/spree,Senjai/spree,xuewenfei/solidus,tesserakt/clean_spree,keatonrow/spree,yomishra/pce,firman/spree,pervino/spree,vulk/spree,jaspreet21anand/spree,jparr/spree,sideci-sample/sideci-sample-spree,TimurTarasenko/spree,robodisco/spree,carlesjove/spree,calvinl/spree,yiqing95/spree,adaddeo/spree,dandanwei/spree,shaywood2/spree,keatonrow/spree,jsurdilla/solidus,StemboltHQ/spree,FadliKun/spree,karlitxo/spree,groundctrl/spree,Lostmyname/spree,watg/spree,zamiang/spree,StemboltHQ/spree,reidblomquist/spree,Mayvenn/spree,Ropeney/spree,tailic/spree,pjmj777/spree,thogg4/spree,Engeltj/spree,fahidnasir/spree,reinaris/spree,tancnle/spree,jeffboulet/spree,shekibobo/spree,pulkit21/spree,berkes/spree,woboinc/spree,tomash/spree,omarsar/spree,shioyama/spree,tancnle/spree,Nevensoft/spree,jasonfb/spree,shioyama/spree,vcavallo/spree,firman/spree,builtbybuffalo/spree,nooysters/spree,DynamoMTL/spree,welitonfreitas/spree,biagidp/spree,useiichi/spree,omarsar/spree,LBRapid/spree,lsirivong/solidus,SadTreeFriends/spree,patdec/spree,scottcrawford03/solidus,dandanwei/spree,karlitxo/spree,vmatekole/spree,siddharth28/spree,vinsol/spree,carlesjove/spree,dotandbo/spree,madetech/spree,mindvolt/spree,Arpsara/solidus,Mayvenn/spree,reinaris/spree,KMikhaylovCTG/spree,Machpowersystems/spree_mach,caiqinghua/spree,trigrass2/spree,joanblake/spree,radarseesradar/spree,useiichi/spree,forkata/solidus,bricesanchez/spree,Migweld/spree,jspizziri/spree,lyzxsc/spree,lsirivong/solidus,trigrass2/spree,joanblake/spree,piousbox/spree,grzlus/solidus,shaywood2/spree,archSeer/spree,NerdsvilleCEO/spree,tesserakt/clean_spree,ayb/spree,woboinc/spree,beni55/spree,groundctrl/spree,tomash/spree,vcavallo/spree,Hates/spree,pjmj777/spree,jasonfb/spree,yushine/spree,siddharth28/spree,camelmasa/spree,biagidp/spree,vinsol/spree,progsri/spree,bricesanchez/spree,bonobos/solidus,quentinuys/spree,lsirivong/spree,quentinuys/spree,RatioClothing/spree,cutefrank/spree,alejandromangione/spree,gregoryrikson/spree-sample,Migweld/spree,azranel/spree,zamiang/spree,yomishra/pce,zaeznet/spree,Hawaiideveloper/shoppingcart,TrialGuides/spree,yushine/spree,dotandbo/spree,jasonfb/spree,biagidp/spree,abhishekjain16/spree,PhoenixTeam/spree_phoenix,rajeevriitm/spree,welitonfreitas/spree,project-eutopia/spree,DynamoMTL/spree,grzlus/solidus,orenf/spree,edgward/spree,archSeer/spree,Boomkat/spree,locomotivapro/spree,jordan-brough/spree,watg/spree,bonobos/solidus,abhishekjain16/spree,lsirivong/spree,xuewenfei/solidus,odk211/spree,kewaunited/spree,lsirivong/solidus,thogg4/spree,Senjai/solidus,vcavallo/spree,athal7/solidus,miyazawatomoka/spree,knuepwebdev/FloatTubeRodHolders,jimblesm/spree,jeffboulet/spree,richardnuno/solidus,PhoenixTeam/spree_phoenix,pervino/spree,moneyspyder/spree,ayb/spree,keatonrow/spree,Arpsara/solidus,keatonrow/spree,progsri/spree,ujai/spree,Hawaiideveloper/shoppingcart,Engeltj/spree,jaspreet21anand/spree,radarseesradar/spree,shaywood2/spree,Kagetsuki/spree,sideci-sample/sideci-sample-spree,Senjai/spree,zaeznet/spree,karlitxo/spree,devilcoders/solidus,pjmj777/spree,yomishra/pce,ahmetabdi/spree,kewaunited/spree,jaspreet21anand/spree,woboinc/spree,ramkumar-kr/spree,jeffboulet/spree,Machpowersystems/spree_mach,vulk/spree,abhishekjain16/spree,tesserakt/clean_spree,trigrass2/spree,JuandGirald/spree,hifly/spree,dafontaine/spree,freerunningtech/spree,dandanwei/spree,grzlus/spree,DarkoP/spree,carlesjove/spree,vinayvinsol/spree,dafontaine/spree,caiqinghua/spree,ramkumar-kr/spree,LBRapid/spree,jordan-brough/solidus,derekluo/spree,agient/agientstorefront,agient/agientstorefront,ayb/spree,berkes/spree,ramkumar-kr/spree,priyank-gupta/spree,delphsoft/spree-store-ballchair,gautamsawhney/spree,lyzxsc/spree,softr8/spree,jspizziri/spree,moneyspyder/spree,forkata/solidus,grzlus/solidus,sunny2601/spree,orenf/spree,omarsar/spree,AgilTec/spree,ramkumar-kr/spree,hoanghiep90/spree,alvinjean/spree,progsri/spree,raow/spree,rbngzlv/spree,dafontaine/spree,robodisco/spree,cutefrank/spree,jeffboulet/spree,assembledbrands/spree,Kagetsuki/spree,derekluo/spree,athal7/solidus,maybii/spree,piousbox/spree,scottcrawford03/solidus,sliaquat/spree,net2b/spree,Boomkat/spree,tomash/spree,locomotivapro/spree,devilcoders/solidus,locomotivapro/spree,athal7/solidus,Hates/spree,Boomkat/spree,robodisco/spree,alvinjean/spree,DarkoP/spree,rbngzlv/spree,raow/spree,mleglise/spree,yushine/spree,camelmasa/spree,jordan-brough/solidus,hifly/spree,nooysters/spree,jaspreet21anand/spree,degica/spree,TrialGuides/spree,edgward/spree,adaddeo/spree,Lostmyname/spree,mleglise/spree,lyzxsc/spree,ckk-scratch/solidus,ujai/spree,brchristian/spree,hifly/spree,beni55/spree,reidblomquist/spree,quentinuys/spree,shekibobo/spree,fahidnasir/spree,Mayvenn/spree,AgilTec/spree,Engeltj/spree,NerdsvilleCEO/spree,DarkoP/spree,azranel/spree,vinsol/spree,shekibobo/spree,useiichi/spree,devilcoders/solidus,sfcgeorge/spree,Hawaiideveloper/shoppingcart,Senjai/solidus,raow/spree,DarkoP/spree,firman/spree,wolfieorama/spree,patdec/spree,jimblesm/spree,yushine/spree,wolfieorama/spree,vcavallo/spree,dandanwei/spree,hoanghiep90/spree,shekibobo/spree,joanblake/spree,agient/agientstorefront,alejandromangione/spree,APohio/spree,berkes/spree,hifly/spree,imella/spree,shaywood2/spree,forkata/solidus,Lostmyname/spree,grzlus/solidus,reinaris/spree,welitonfreitas/spree,TimurTarasenko/spree,CiscoCloud/spree,rakibulislam/spree,ayb/spree,ahmetabdi/spree,softr8/spree,grzlus/spree,project-eutopia/spree,vulk/spree,joanblake/spree,Mayvenn/spree,priyank-gupta/spree,quentinuys/spree,StemboltHQ/spree,welitonfreitas/spree,dotandbo/spree,Engeltj/spree,vinayvinsol/spree,JDutil/spree,azclick/spree,CiscoCloud/spree,priyank-gupta/spree,builtbybuffalo/spree,CiscoCloud/spree,scottcrawford03/solidus,KMikhaylovCTG/spree,caiqinghua/spree,TrialGuides/spree,Lostmyname/spree,Ropeney/spree,assembledbrands/spree,JDutil/spree,TrialGuides/spree,orenf/spree,jparr/spree,zamiang/spree,edgward/spree,JuandGirald/spree,builtbybuffalo/spree,madetech/spree,Ropeney/spree,camelmasa/spree,beni55/spree,patdec/spree,moneyspyder/spree,JDutil/spree,njerrywerry/spree,abhishekjain16/spree,Arpsara/solidus,brchristian/spree,azranel/spree,kewaunited/spree,sliaquat/spree,vinsol/spree,sliaquat/spree,Hawaiideveloper/shoppingcart,carlesjove/spree,hoanghiep90/spree,ahmetabdi/spree,sunny2601/spree,pulkit21/spree,JDutil/spree,piousbox/spree,vinayvinsol/spree,odk211/spree,fahidnasir/spree,pervino/spree,DynamoMTL/spree,alejandromangione/spree,vulk/spree,siddharth28/spree,dotandbo/spree,alejandromangione/spree,ujai/spree,tailic/spree,vmatekole/spree,gautamsawhney/spree,nooysters/spree,gregoryrikson/spree-sample,CJMrozek/spree,miyazawatomoka/spree,radarseesradar/spree,Arpsara/solidus,maybii/spree,grzlus/spree,azclick/spree,odk211/spree,karlitxo/spree,thogg4/spree,alepore/spree,tancnle/spree,progsri/spree,knuepwebdev/FloatTubeRodHolders,groundctrl/spree,patdec/spree,Nevensoft/spree,yiqing95/spree,rakibulislam/spree,Nevensoft/spree,project-eutopia/spree,madetech/spree,camelmasa/spree,RatioClothing/spree,CJMrozek/spree,bjornlinder/Spree,priyank-gupta/spree,bonobos/solidus,TimurTarasenko/spree,lyzxsc/spree,NerdsvilleCEO/spree,degica/spree,richardnuno/solidus,Boomkat/spree,TimurTarasenko/spree,PhoenixTeam/spree_phoenix,SadTreeFriends/spree,caiqinghua/spree,agient/agientstorefront,freerunningtech/spree,JuandGirald/spree,miyazawatomoka/spree,jimblesm/spree,surfdome/spree,rbngzlv/spree,devilcoders/solidus,useiichi/spree,berkes/spree,volpejoaquin/spree,lsirivong/spree,AgilTec/spree,sfcgeorge/spree,shioyama/spree,athal7/solidus,ckk-scratch/solidus,cutefrank/spree,siddharth28/spree,azranel/spree,volpejoaquin/spree,FadliKun/spree,reidblomquist/spree,volpejoaquin/spree,calvinl/spree,cutefrank/spree,groundctrl/spree,archSeer/spree,delphsoft/spree-store-ballchair,alepore/spree,jsurdilla/solidus,piousbox/spree,richardnuno/solidus,bonobos/solidus,brchristian/spree,Senjai/spree,azclick/spree,kewaunited/spree,locomotivapro/spree,tesserakt/clean_spree,volpejoaquin/spree,beni55/spree,imella/spree,lsirivong/spree,reidblomquist/spree,derekluo/spree,SadTreeFriends/spree,FadliKun/spree,odk211/spree,alvinjean/spree,jimblesm/spree,CJMrozek/spree,net2b/spree,DynamoMTL/spree,yiqing95/spree,robodisco/spree,njerrywerry/spree,sfcgeorge/spree,trigrass2/spree,calvinl/spree,watg/spree,maybii/spree,vmatekole/spree,softr8/spree,jspizziri/spree,sfcgeorge/spree,brchristian/spree,njerrywerry/spree,LBRapid/spree,surfdome/spree,jparr/spree,gautamsawhney/spree,zaeznet/spree,tomash/spree,alepore/spree,Migweld/spree,jparr/spree,SadTreeFriends/spree,KMikhaylovCTG/spree,sunny2601/spree,sliaquat/spree,hoanghiep90/spree,maybii/spree,AgilTec/spree,ckk-scratch/solidus,archSeer/spree,imella/spree,assembledbrands/spree,bricesanchez/spree,dafontaine/spree,orenf/spree,lsirivong/solidus,bjornlinder/Spree,Ropeney/spree,Senjai/solidus,alvinjean/spree,pervino/solidus,tancnle/spree,adaddeo/spree,rajeevriitm/spree,APohio/spree,degica/spree,rajeevriitm/spree,sideci-sample/sideci-sample-spree,adaddeo/spree,pulkit21/spree,KMikhaylovCTG/spree,pervino/solidus,scottcrawford03/solidus,bjornlinder/Spree,Kagetsuki/spree,jordan-brough/solidus,madetech/spree,builtbybuffalo/spree,JuandGirald/spree,CJMrozek/spree,jordan-brough/spree,derekluo/spree,knuepwebdev/FloatTubeRodHolders,yiqing95/spree,jordan-brough/spree,miyazawatomoka/spree,rajeevriitm/spree,gautamsawhney/spree,moneyspyder/spree,gregoryrikson/spree-sample,xuewenfei/solidus,zamiang/spree,Hates/spree,APohio/spree,fahidnasir/spree,gregoryrikson/spree-sample,mindvolt/spree,CiscoCloud/spree,sunny2601/spree,raow/spree,pervino/spree,Machpowersystems/spree_mach,Kagetsuki/spree,Nevensoft/spree,rakibulislam/spree,jsurdilla/solidus,Hates/spree,project-eutopia/spree,mindvolt/spree,net2b/spree,PhoenixTeam/spree_phoenix,reinaris/spree,delphsoft/spree-store-ballchair,pervino/solidus,Migweld/spree,edgward/spree,Senjai/solidus,firman/spree,radarseesradar/spree,wolfieorama/spree,thogg4/spree,grzlus/spree,surfdome/spree,ckk-scratch/solidus,azclick/spree,freerunningtech/spree,wolfieorama/spree,zaeznet/spree,jspizziri/spree,delphsoft/spree-store-ballchair,jasonfb/spree,tailic/spree,xuewenfei/solidus,ahmetabdi/spree,calvinl/spree,jsurdilla/solidus,pervino/solidus,mindvolt/spree,jordan-brough/solidus,njerrywerry/spree