Release bot for everyone: let one deployment track multiple projects

[TomasTomecek]

This is closely related to #112

Since one deployment of release bot is able to track only a single github project now, let's remove this limitation and figure out how the bot can track multiple projects.

The short-term solution would be to hard-code the list in the config file. Once #112 is implemented, this feature has to be integrated with solution from #112.