Add processor for Koschei messages
Test for KoscheiProcessor
Fix out-of-sync docstring
Remove build_task_id and repo_id fields from the message

They are not very helpful, because you still need to visit Koschei's web
interface to know the reason. And they make sense only for certain state
transitions
Add subtitle for transition from ignored
Include repo and koji instance in subtitle
Merge pull request #155 from msimacek/feature/koschei

Feature/koschei