problemset model
Merge remote-tracking branch 'upstream/master'

Conflicts:
	web/handlers/user.py
add decorator
o
add get_problemsets
add get_problemsets
Merge branch 'master' of https://github.com/roba269/gf2
Merge pull request #27 from charliezhang/master

Add UserManager for user info. en/ch Support
address comments
Merge pull request #22 from roba269/master

Add get_problemsets api and some other util functions