Upgrade dependency on vCloud Core to 0.13.0

Upgrade dependency on vCloud Core to 0.13.0. An error will now be raised
if your `FOG_CREDENTIAL` environment variable does not match the
information stored against a vCloud Director session referred to by
`FOG_VCLOUD_TOKEN`, so as to guard against accidental changes to the
wrong vCloud Director organization.
Release version 0.7.0
Merge pull request #55 from gds-operations/78700334-upgrade_core

[#78700334] Release version 0.7.0