[vcloud_director] fixes so that non configured gateway are supported
[google|storage] ensure connection uses correct URI

This defers establishing the connection until the proper scheme, host
and port can be determined from the request, as these are now invalid
Excon request parameters.
Merge pull request #2295 from burns/google_storage

[google|storage] Fix integration with new excon version.
Merge pull request #2291 from alphagov/empty_edge_gateway_support

[vcloud_director] fixes so that non configured gateway are supported