Cannot work with multiple resource groups in Azure ARM

Currently the Azure ARM provider assumes one resource group for each location, with a name in the form: prefix-location. Whenever a resource is created or looked up, jclouds builds that resource group name and uses it, ignoring all others.

The ComputeService.listNodes implementation, however, lists the VMs in all resource groups, and that causes conflicts, since the transformation functions and other parts of the code only consider the "default" resource group.

A more flexible approach should be used:

• Let users configure the name of a default resource group to be used to create resources.
• When listing existing resources, jclouds should try to find them in any resource group.
• It would be good to change the IDs of the entities returned by jclouds from location/name to resourcegroup/name, as it better identifies the resource.