JCLOUDS-607: ComputeService.createNodesInGroup throws NPE on FloatingIPA...

Addresses possible returned null value from 'FloatingIPApi.create()'. If upon check we find null then throw InsufficientResourcesException. This in turn will make a second check at IP allocation by iterating through 'FloatingIPApi.list()' and grabbing an available IP. If this subsequent call fails then re-throw InsufficientResourcesException.
I wouldn't use exceptions to control the execution flow. I understand it might be trivial here, but it is in general a bad practice.

Could the code inside the catch be moved out to a method, call it from the catch and when the returned ip is `null`, and remove that `throws`?