[CLC-1231] Clear Completed Google Tasks endpoint: Adding proxy level endpoint

[CLC-1231] VCR namespace fix, pushing recording-centric test for tasks into /recordings, updating tests

[CLC-1231] Merged model integration + tests

[CLC-1231] Route, controller, tests wiring
Merge pull request #737 from yuhunglin/CLC-1231

[CLC-1231] Clear Completed Google Tasks endpoint