Gobject conversion. Changes in way we handle magnitudes due to upstream bug.

See the code for rationale of the new way of handling things, how we work
around the bug, and the new added test for the required method.

Note that buffer_handler is NOT working, so no recording of audio samples is possible.
This is fixed in a subsequent commit.
cleanup of gst names and argv trick
Refactoring of audio file writing code, to have gstreamer do all of the work
Changed GObject calls to solve Saucy deprecation warnings
Updated README with dependencies and stuff