erlang-bitcask source package infomation

- Remove rebar binary from source code 

  Erlang-bitcask's original source codes contains rebar binary.
  The source package of Debian has deleted this binary.

- Remove doc directory from source code
  Erlang-bitcask's original source codes contains pdf file.
  But source code for pdf is not included.
  The source package of Debian has deleted this binary.

 -- Nobuhiro Iwamatsu <iwamatsu@debian.org> Thu, 04 Oct 2012 05:39:47 +0900
