Adds os-aggregates metafiles for api samples

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

Change-Id: I171b28870f98afe2245ce5a9cc1cbe7163ab4ab7
Merge pull request #2 from soulxu/add_metafiles_aggregates

Adds os-aggregates metafiles for api samples