Version Up: 0.1.2.dev

Updated the version strings to the next development version. Had to use 0.1.2a1
instead of the actually correct 0.1.2.dev, because distutils checks for an
incorrect version regex still. So we are not compliant to
http://www.python.org/dev/peps/pep-0440/ yet.

Signed-off-by: Erik Bernoth <erik.bernoth@gmail.com>