Changed trophy logic to use Database

Made "TrophyManager" class and "compute_trophies" method.
Add the TrophyManager to Trophy model.
Create "iftrophy" at reviews/templatatags.py
In the method pull trophy data from database.
Merge branch 'temp1' into hiroki0228

Conflicts:
	reviewboard/accounts/managers.py
	reviewboard/accounts/tests.py