Added a new method cloneable? to check if VMs/Templates can be cloned or not

issue #253
https://bugzilla.redhat.com/show_bug.cgi?id=1122712
The UI currently allows only 1 VM/Template to be cloned at a time, hence we originally planned to write the class method for 1 id only. 
I guess it wouldn't hurt to write it for an array of IDs.
Will make the necessary changes.