Point Of Interest (Quest Details etc.)

@wsuchy , @jacekjursza and me - decided to implement QuestDetails API and NearbyQuests API (+ all related stuff) in single brunch (because these tasks are strongly coupled).

At the moment - this pull request must be only reviewed and not merged!
To be honest, I was lazy and just used code from Stackoverflow: http://stackoverflow.com/a/10473026 :-)
I will refactor code - to use functions from GlobalFunctions.php