Complete implementation of Mixed Reality Capture API

[david-c-kline]

Shared project\HoloLens\MixedRealityCapture.cs

Specifically the live streaming methods.

[david-c-kline]

The following APIs are yet to be implemented:
api/holographic/mrc/settings
api/holographic/stream/live.mp4
api/holographic/stream/live_high.mp4
api/holographic/stream/live_low.mp4
api/holographic/stream/live_med.mp4

[david-c-kline]

MRC stream APIs were checked in with PR #184