Support for size of gravatar image

Added support for the size (s) argument in the Gravatar API
Update modelx.py
Update modelx.py

this breaks compatibility
Update UserX, with back compatibility
Update user_list.html
Update profile.html
Merge branch 'patch-1' of github.com:xcash/gae-init
Fixed avatar for HDPI screens in user_list.html
Updated Bootstrap to 3.0.1