Add bzip2 multi-stream support

[joachimmetz]

From: https://docs.python.org/2/library/bz2.html

Note This class does not support input files containing multiple streams (such as those produced
by the pbzip2 tool). When reading such an input file, only the first stream will be accessible.
If you require support for multi-stream files, consider using the third-party bz2file module
(available from PyPI). This module provides a backport of Python 3.3’s BZ2File class,
which does support multi-stream files.

https://github.com/nvawda/bz2file