Fail2ban as python module

Reference #26, I've made some changes such that fail2ban is installed as python module, therefore resolving the issue with python paths.

The structure I've gone with is renaming _common_ to _fail2ban_, and then _server_ and _client_ sit under this.

I've put the pull against 0.9, as although it's not a major change in how fail2ban runs (assuming imports work okay), it may effect how package maintainers package it.

Feedback welcome :smile: