Various edge fixes

Details in webrtc/adapter@v3.1.6...v3.1.7

Fixes stats type in Edge and fixes facingMode polyfill on Chrome 53-56

Full details in webrtc/adapter@v3.1.5...v3.1.6

Make sender.dtmf be null for video tracks + shim removeStream.

Full details in webrtc/adapter@v3.1.4...v3.1.5

Improved Safari detection, Shim Element.setAttribute('src', URL.createObjectURL(stream)), Shim pc.getSenders() with dtmf ontop of Chrome's dtmf support and test cases improvements

Full details can be found at webrtc/adapter@v3.1.3...v3.1.4

Add icegathertingstatechange event for MS edge and removed a clone track workaround

Full details of changes in webrtc/adapter@v3.1.2...v3.1.3

Reverts edge RTX fixes and disables it again, fixes getStats regression for older Firefox releases (prior 48)

Details in webrtc/adapter@v3.1.1...v3.1.2

Fixes srcObject recursion, various edge issues and restricts the new getStats

List of commits: webrtc/adapter@v3.1.0...v3.1.1

Shim URL.createObjectURL(stream) using srcObject

v3.1.0

bump to 3.1.0

Fix node engine requirement

v3.0.1

bump to 3.0.1

Adapter 3.0 - Major getStats() overhaul

Details in https://groups.google.com/d/topic/discuss-webrtc/OXqm0tjg8hs/discussion