Adding support for parallel recording sessions.

- Added setOutputFileAuxiliary to pass the auxiliary file descriptor. The java
interface through JNI will be checked in next.

- renamed setupCameraSource to setupCamera as the function just sets the camera.
- Added setupCameraSource which sets up the camera source. This functionality
  was in setupVideoEncoder before.
- setupVideoEncoder now takes in a cameraSource instead of creating it on it
  own.

- Refactored startMPEG4Recording() to use setupMPEG4Recording,
  setupMPEG4MetaData.
    - setupMPEG4Recording() takes in file descriptor, bitrates to setup a mpeg4
      writer. This function can be called multiple times to setup multiple
      writers.
    - Added setupMPEG4MetaData() for setting up the meta data for mpeg4 writer.
  startMPEG4Recording() now calls setupMPEG4Recording, setupMPEG4MetaData for
  each recording session.

Change-Id: I07f5334a1ff8e12a36f58e94129fcfa6add2208b