* Alerting: Use a default configuration and periodically poll for new ones
Use a default configuration to make sure we always start the grafana
instance. Then, regularly poll for new ones.
I've also made sure that failures to apply configuration do not stop the
Grafana server but instead keep polling until it is a success.
* first pass
* add instance manager
* fix tests
* remove dead code
* unexport fields
* cleanup
* remove ds instance from executor
* cleanup
* inline im
* remove old func
* get error working
* unexport field
* let fe do its magic
* fix channel name
* revert some tsdb changes
* fix annotations
* cleanup
