Add sentry integration module

Module for enabling raven initializing to report to sentry.

Based on feedback from my presentation at odoo days 2014

Related project: https://github.com/gisce/openerp-sentry

~~Todo~~
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- [x] Add git module version overwrite to raven
- [x] Overwrite the except_orm message pop-up with something a little more friendly to the user **(Help wanted)**
- [ ] Enable tests with sentry server in travis
The code should work with and without git, bzr python libraries, so I see nothing wrong with having these be optional dependencies.