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
----

- [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
- [x] Don't log `SessionExpiredException`
- [x] Don't log `TransactionRollbackError` ?
- [x] Do a better job at sanitizing the passwords (openerp/netsvc.py in dispatch_rpc )
    * Maybe exclude dispatch_rpc from the traceback
- [ ] ~~Enable tests with sentry server in travis~~