v0.22
- [IMPROVEMENT] Add test button to test exporters from Promgen
- [IMPROVEMENT] Further simplify notifications by dedeuplicating labels/annotations
- [BUGFIX] Ensure we properly raise Exceptions if a sender fails
- [IMPROVEMENT] Urlize comments in Silence list (for linking to bug tracker)
- [IMPROVEMENT] Add description field to rules so developers can add additional context
- [IMPROVEMENT] Update Django to 1.11