Implemented a Bzip2Decoder

Motivation:

Bzip2Decoder provides receiving data compressed in bzip2 format.

Modifications:

Added classes:
- Bzip2Decoder
- Bzip2Constants
- Bzip2BlockDecompressor
- Bzip2HuffmanStageDecoder
- Bzip2MoveToFrontTable
- Bzip2Rand
- Crc32
- Bzip2DecoderTest

Result:

Implemented and tested new decoder which can uncompress incomming data in bzip2 format.
This implementation based on Matthew J. Francis's work:
https://code.google.com/p/jbzip2/
@normanmaurer @trustin 
Any ideas?