py-bumpversion: import version 0.5.3

bumpversion is a small command line tool to simplify releasing software by
updating all version strings in your source code by the correct increment. It
also creates commits and tags:

- version formats are highly configurable;
- it works without any VCS, but happily reads tag information from and writes
  commits and tags to Git and Mercurial if available;
- it just handles text files, so it's not specific to any programming language.

(khorben)