Advbumpversion

- Add --verbose option (`21 <https://github.com/peritus/bumpversion/issues/21>`_ `30 <https://github.com/peritus/bumpversion/issues/30>`_)
- Allow option --serialize multiple times

- Fix: --parse/--serialize didn't work from cfg (`34 <https://github.com/peritus/bumpversion/issues/34>`_)

- Don't fail if git or hg is not installed (thanks keimlink)
- "files" option is now optional (`16 <https://github.com/peritus/bumpversion/issues/16>`_)
- Fix bug related to dirty work dir (`28 <https://github.com/peritus/bumpversion/issues/28>`_)

- Fix --tag default (thanks keimlink)

- add {now} and {utcnow} to context
- use correct file encoding writing to config file. NOTE: If you are using
Python2 and want to use UTF-8 encoded characters in your config file, you
need to update ConfigParser like using 'pip install -U configparser'
- leave current_version in config even if available from vcs tags (was
confusing)
- print own version number in usage
- allow bumping parts that contain non-numerics
- various fixes regarding file encoding

- bugfix: tag_name and message in .bumpversion.cfg didn't have an effect (`9 <https://github.com/peritus/bumpversion/issues/9>`_)