Use released fog 0.15.0.
Merge branch 'fog_0_15' into vcloud_director

* fog_0_15:
  Use released fog 0.15.0.
Use mutli_json gem instead of json.
Merge branch 'multi_json' into vcloud_director

* multi_json:
  Use mutli_json gem instead of json.
Allow use of fog's credentials file.
Merge branch 'credentials' into vcloud_director

* credentials:
  Allow use of fog's credentials file.

Conflicts:
	lib/provisioner/provisioner.rb