Use OAuth2 for Grafana login authentication

This release includes and update to Grafana v4.5.2. With this change we are also using OAuth login exclusively.

This release includes alert changes from #88

This release includes support for snmp-exporter.

Update resource limits for mlab-staging & mlab-oti

Merge pull request #72 from stephen-soltesz/master

Add notes for upgrading resource limits

Alertmanager Github Receiver

Includes the v0.0 github receiver running in mlab-oti.

Initial Release

This is the first version to support autodeploy to mlab-oti from tags.