Merge pull request #233 from ArtemSerga/parent

Need u'' prefix to avoid encoding error in some cases (UnicodeEncodeError: 'ascii' codec can't encode characters)
Use joined load instead of subquery load due to performance concerns
Merge branch 'master' of github.com:mrjoes/flask-admin
Fixed form rendering logic
Fixed #235
Fixed mongoengine boolean filter. Fixes #238
Python 3 metaclass magic
Get rid of flask-wtf dependency
Additional flask-wtf cleanup fixes
Python 3 fixes.
Unit test fixes
Test fixes
Wording
Python 2 fixes
Python 2 fixes
pymongo backend fixes
Simple fileadmin test
Fixed fileadmin
Cleaned up examples
Updated tests and removed as_unicode() compat helper