Add sentry integration module

Module for enabling raven initializing to report to sentry.

Based on feedback from my presentation at odoo days 2014

Todo
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- [ ] Add git module version overwrite to raven
- [ ] Overwrite the except_orm message pop-up with something a little more friendly to the user **(Help wanted)**
How, I think that it is necessary to change the travis file project, to install extra lib, that could be not be present on Travis System.
Like in my PR: https://github.com/OCA/server-tools/pull/50/files#diff-0

This should fix Travis: https://travis-ci.org/OCA/server-tools/jobs/33630905#L310

Don't you think ?
Regards.