Adds V3 API samples for cells and multinic

Adds V3 API samples for cells and multinic extensions.
Bundling them together to save on review load

Partially implements blueprint v3-api-unittests
Partially implements blueprint v3-api-specification

Change-Id: I50840b3d900fbc8ff4f655e4188cc886d7065729
Add metafiles for cells, multinic

Converts cells, multinic api sample to create meta files
for api sample docs. We use this to auto generate the
specification document.

Change-Id: Ia8f597d42661deff8e50424500581abdc4f677dd
Merge pull request #12 from Ivan-Zhu/cell_doc

Cell doc