If a new user receives a mention, quote or response to their post, allow
them to continue posting in a topic.
FEATURE: support for enabling all upload file types

BUGFIX: authorized extensions is now case insensitive
move custom fields into its own concern
Add CustomFields to Post, Category and Group
fix double save missing error by using copy not actual reference
Add Custom Fields on Topics
Add Support for Arrays to CustomFields
Move Concern from lib into app/models. refs #2279
use more explicit naming to prevent name clashes. fixes build.
Ensure Reload reloads custom_fields, too
Track the ip address where user was registered
Support 404 routes in the Ember App
Add an integration test for the new Ember 404 route
apparently that's not markdown-ified
FIX: Don't show `undefined` query params
more accurate description of newuser_max_replies
User new `/my/preferences` route in an email
Support for linking to static pages with hash URLs like `#section`. Also
refactor of static code to be more idomatic.
FIX: Changed fixture paths
FIX: preferences URL changed