Add V3 API samples for config-drive

Partially implements bp v3-api-extension-versioning

Change-Id: Id589ddced8c30089bacbb3eca81d4b9238901a91
Add config-drive metafile for api sample

Converts config-drive api sample to create meta files for api sample docs.
We use this to auto generate the specification document

Change-Id: I4856552df0b88d0a0adbefb5cbb56a2e12347695
Merge pull request #14 from soulxu/add_metafiles_config_drive

Add config drive metafile for api sample