[vsphere] vsphere fixes for latest HEAD changes

Correct use of Fog.mock? instead of ENV
Use find_raw_datacenter to avoid the need of extra permissions
Find datastores in subfolders
nil pointer when finding vm

I'm working on better mocks at another branch but I'm not done yet, need access to a vsphere server which hopefully will happen next week
https://github.com/maestrodev/fog/tree/vsphere-tests