Coveralls.io

Inspired by another repo and @grooverdan's coverage additions (#133), I've added [coveralls.io](https://coveralls.io) integration with Travis CI. I believe that the fail2ban repo will need to allow access from [coveralls.io](https://coveralls.io), which can be done via the website. Limited to python2.6 and python2.7 due to support limitation for _coveralls_ python library.

Example output from my fail2ban fork: https://coveralls.io/r/kwirk/fail2ban