Add vendor_data2 support for ConfigDrive source

[cvstealth]

Proposed Commit Message

Summary: Support vendor_data2 as a source of data when using a ConfigDrive

When using a ConfigDrive as a data source for cloud-init only vendordata is currently evaluated.  This patch adds support for vendor_data2 when used with ConfigDrive and aligns with the same feature parity that is found when using the OpenStack Neutron metadata service (DataSourceOpenStack.py).

Test Steps

Generate a OpenStack configuration drive that contains vendor_data2.json and verify the context of the JSON file are properly executed.

Checklist:

• My code follows the process laid out in the documentation
• I have updated or added any unit tests accordingly
• I have updated or added any documentation accordingly

[TheRealFalcon]

Thanks for contributing to cloud-init!

This PR looks good to me. CI never returned from Travis, so I'm going to close and re-open this PR to re-trigger CI. If that passes then we should be good to merge.