[core] fix attribute squashing with : in key
[core] fix attribute squashing with : in key

It can happen, that the squashing options conatins a : within its key,
for example: :squash => :'ovf:Item' . However this fails if we don't
quote the used symbol.

Note that :a == :'a', hence we don't change anything on how things work.

dtdream/fog,theforeman/fog,zephyrean/fog,phillbaker/fog,Ladas/fog,nandhanurrevanth/fog,MSOpenTech/fog,b0e/fog,mohitsethi/fog,cocktail-io/fog,mohitsethi/fog,adamleff/fog,ack/fog,fog/fog,runtimerevolution/fog,mitchlloyd/fog,seanhandley/fog,surminus/fog,ManageIQ/fog,sideci-sample/sideci-sample-fog,dLobatog/fog,theforeman/fog,rackspace/fog,sferik/fog,fog/fog,kongslund/fog,mavenlink/fog,kongslund/fog,dustacio/fog,martinb3/fog,surminus/fog,pyama86/fog,bryanl/fog,mavenlink/fog,rackspace/fog,backupify/fog,pyama86/fog,github/fog,12spokes/fog,backupify/fog,sideci-sample/sideci-sample-fog,cocktail-io/fog,nicolasbrechet/fog,brilliomsinterop/fog,pravi/fog,TerryHowe/fog,eLobato/fog,github/fog,SpryBTS/fog,duhast/fog,nandhanurrevanth/fog,yyuu/fog,Programatica/fog,glennpratt/fog,seanhandley/fog,papedaniel/fog,b0ric/fog,10io/fog,alphagov/fog,bdunne/fog,dpowell7/fog,mitchlloyd/fog,nicolasbrechet/fog,martinb3/fog,b0ric/fog,dhague/fog,asebastian-r7/fog,ManageIQ/fog,phillbaker/fog,eLobato/fog,yyuu/fog,alphagov/fog,lwander/fog,nalabjp/fog,joshisa/fog,displague/fog,adecarolis/fog,unorthodoxgeek/fog,glennpratt/fog,unorthodoxgeek/fog,plribeiro3000/fog,dustacio/fog,lwander/fog,brilliomsinterop/fog,ack/fog,dLobatog/fog,joshisa/fog,duhast/fog,joshmyers/fog,nalabjp/fog,bryanl/fog,covario-cdiaz/fog,petems/fog,plribeiro3000/fog,dhague/fog,icco/fog,icco/fog,brilliomsinterop/fog,brandondunne/fog,TerryHowe/fog,zephyrean/fog,joshmyers/fog,zephyrean/fog,MSOpenTech/fog,adamleff/fog,petems/fog,phillbaker/fog,NETWAYS/fog,asebastian-r7/fog,pravi/fog,adecarolis/fog,papedaniel/fog,displague/fog,sapcc/fog,SpryBTS/fog,10io/fog,runtimerevolution/fog,NETWAYS/fog,covario-cdiaz/fog,nandhanurrevanth/fog,sapcc/fog,Programatica/fog,dtdream/fog,Ladas/fog