autotools: added EXTRA_DIST

Now sources can be distributed with `make dist-bzip2` command, so no
need to make tarball manually. Current patch takes into account the
status (release or development) and puts .git/HEAD, .git/index to
tarball if necessary.

Unfortunately, current scripts don't add any information about
development status to the version string. Therefore,
profanity-0.5.0.tar.bz2 is got regardless of development or release
status.