To add video recording this patch changes recordable and
audio related class non-dependent.
This moves AudioRecorder handling into AudioRecord class.

Fixes also Audio recording start/stop that not working as waited:
- first start was just creating the file
- recording was started at second "toggle", confusing user.


Change-Id: I07f69b76ad711d7fc4d64e57e78b5704d60b4861
Tuleap: #337