Preliminary support for an Ogg muxer

* BitStrings changed to resemble more of
Erlang bit syntax
* Update parsing SpeexHeader and SpeexComment
to use new Bitstrings
* Ogg muxer changed API to (de)mux instead (un)pack

TODO:
- need to fix granule position and checksum. for
 now they are always 0 which means that libogg
 fails to create the bitstream with invalid
 checksums.
Update app regarding the support for file encoding
Added some tests for ogg