[Openstack|Volumes] available? check method
[Openstack|Volumes] available? check method

available? simply returns whether the volume is being used or its
available. This is convenient for applications using the Fog API to
check if they can use a Volume by calling
```openstack.volumes.select(&:available)```

Renamed to ready?

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