Cloudstack Driver - Create/Delete Network functionality + tests

Functions added on the cloudstack driver:
 
ex_list_network_offering
ex_create_network
ex_delete_network

New Object:
CloudStackNetworkOffering

And some additions to the CloudStackNetwork dictionary
netmask
gatway
vpcid
Could you also add deleteNetworkOffering and createNetworkOffering ? Since you are defining the CloudStackNetworkOffering class, you could add the other methods