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.
Do we know if 'FloatingIPApi.create()' throws an 'InsufficientResourcesException' or will always return null upon unsuccessful allocation? I've no idea how to go about tracking the impl down which is why I ask. If the later we can do away with the try/catch block altogether and only throw the IRE should all attempts to allocate an IP fail. Thoughts?