Bug/user settings + client-side file size validation

- removed complexity of dual forms
- ajaxified edit name
- encapsulated confusingly named methods into better named methods 'user.has_uploaded_image?' & user.has_gravatar?
- client-side file size validation added
- set default to gravatar if user has one
- refactor user avatar setting options into a partial
- refactor avatar/initials condition into a partial
- reimplement permalink feature