[webrtc-stats] new commits pushed by vr000m

The following commits were just pushed by vr000m to https://github.com/w3c/webrtc-stats:

* Add insertedSamplesForDeceleration and removedSamplesForAcceleration (#408)

* Add deceleratedSamples and acceleratedSamples

* Only present for inbound audio tracks

* Fix travis error

* Updated names and definitions

* Sped up
  by henbos
https://github.com/w3c/webrtc-stats/commit/95f3d507235b3d0fec4ff15fe06ebc24ccefea49