add Trove classifiers for issue #24, get version from single place, add ...

...pyfiglet command via entry_points, and bump version to version 0.7.

You may want to double check the Trove classifiers, such as status. I added the Python versions according to `.travis.yml`. I missed the PyPy, if you need me to stack another commit, I can do that.

Fixed a few PEP8 along the way. Bump the version to 0.7, although I didn't intent to update version string, but since I made version string to store in single place -- you can see there were two version `0.6.1` and `0.6.1dev`, which was an error -- so I just made as 0.7. There is also another version string 0.6 in manpage, and I missed it because I grepped `0\.6\.1'.