Error handling improvements
* show error message on UI in case repo toggling fails
* eliminate possibility of creating multiple webhooks
Store comment PNG for all balances of a bounty (Fixes: #22)
* include balance in computation of verification hash for image request
* store hash in db
Refactoring
* use 'owner' for a repo owner everywhere instead of 'login'
Minor
* move cider dependencies to top-level in project file to avoid errors
with tests and migratus
Teemu Patja