Use API interface rather than fog directly

This requires an update to depend on vCloud Core version 0.8.
Add YARD doc directory to gitignore
Update to vCloud Core 0.9.0

This would work with vCloud 0.8.0 but might as well update to latest.
Merge pull request #48 from gds-operations/use-core-not-fog

[#70162466] Use core not fog