[vsphere] Use Fog.mock? as the other providers
Specs can set Fog.mock! without setting the env var
[vsphere] Use find_raw_datacenter instead of get_raw_datacenter

find_raw_datacenter uses the cache of datacenters in list_datacenters, speeding it up. Calls to get_raw_datacenter if not cached
Merge pull request #1769 from maestrodev/fog_mock

[vsphere] Use Fog.mock? as the other providers
Merge pull request #1770 from maestrodev/find_raw_datacenter

[vsphere] Use find_raw_datacenter instead of get_raw_datacenter