Added badges to apps

[zealot128]

I've added 2 badge types that are available for each app.
Badges are a nice way to communicate quality in a README etc.

Thinks that I am not so sure/could be optimized (if somebody wants to help, please feel free!)

• authenticated key -> I've reused the key usage from the atom feed... that makes the token quasi public, and might be a problem when the Atom feed contain sensitive info. Maybe generate a new token per app only for badge usage?
  • Right now, we will only use the badges in private projects, so for us not urgent, but definitely preferable
  • update: added environment BADGE_PUBLIC which the user can decide which approach is more suitable
• Badge Ranges... I've just made some guesses. Not sure how merged problems fell into that etc.
  • Would be great to make the ranges configurable via ENV config etc. (maybe later)
• only added 2 smoke tests, had not the time to add thorough test of the logic (as ranges not sure right now)
• other badge ideas? class infrastructure is there to add other badge types easily