Upgrading Flask-WTF and more

This breaking the functionality, but it's been a while :)
Can we somehow check if we need this line in any way (probably in the gae-init-auth) https://github.com/mitsuhiko/flask-oauth/commit/8bcba9a5f3db9fdcd2aff9e31245a33a053c5c39

Otherwise we can write `flask-oauth==0.12` as it's not updated: https://github.com/mitsuhiko/flask-oauth/issues/65