Make even more CSS external

GWT's class obfuscation makes it impossible for users to write
their own CSS that won't break on upgrade. This further helps preserve
class names so uses can continue to rely on the names and use
GerritSite.css to it full ability.
Replace favicon with aokp icon
add gravatar to core plugins
Update Icons
Revert "Move change id and status to left side of ChangeScreen2"

This reverts commit e8f61bda2e28a37578c86e7e6ec4f8d40a810271.