Proper Sentry integration

[Erik van Zijst]

Such that you get those nice clickable tracebacks.

This is currently blocked by Raven's inability to accept arbitrary stack frames: https://github.com/dcramer/raven/issues/111

[Erik van Zijst]

Issue #2 was marked as a duplicate of this issue.

[Stefano Rivera]

The raven repo moved: https://github.com/getsentry/raven-python/issues/111

[Ian Wilson]

I've submitting a fix for this in the following pull request.

https://bitbucket.org/evzijst/dogslow/pull-request/9/proper-sentry-integration

[Erik van Zijst]

Thanks @ianawilson, fixed!