[Add] VAD support to detect when speech ends
[Fix] memory leak on the WITVad objc wrapper
Using a better algoritm for the VAD
[clean] cleaning after code review w/ @blandinw
[Fix] WITRecorder and WITUploader were used as signleton objects
Adding WITRecordingSession to manage all the...

objects involved in a recording session
[Add] support attaching custom data to the request

and getting it back in the response callback.
Link the VAD error tracking system to the WIT Backend
Cleaning vad tracker
Merge pull request #21 from wit-ai/vad-stop

[Add] VAD support to detect when speech ends