Merge pull request #1 from zertico/refactor_structure

Refactoring Structure. Defining Compute inside XenServer
Updating all references to fog organization
Changing Structure. Service should be inside the Compute namespace.
The request models need to be refactored yet. This changes affect only
the models.
Merge pull request #2 from fog/updating_links

Updating all references to fog organization
Merge pull request #3 from fog/reworking_structure

Changing Structure. Service should be inside the Compute namespace.
Moving XenServer Service classes to dedicated files for each
Namespaced Models to let the requests in a different folder
Moving Requests folder to inside xen_server folder
Moved Parsers namespace to its own folder inside fog folder
Moving XenServer classes to dedicated files for each
Moving Utilities and Version to XenServer folder
Fixing require errors on request files
Fixed Models references on Collections
Fix for Constant loading. FogCore always try to find the models inside the Service Namespace
Workaround to fix loading.
This hack is need until the fog-core accepts the Compute namespace to
hold the Service's. FogCore related code can be found in:
https://github.com/fog/fog-core/blob/master/lib/fog/compute.rb#L57