move concerns to the model/concerns
escape gravatar URLs to comply with W3C standards

This fixes an HTML validation error due to & not being properly escaped on the gravatar URLs.
fixes user specs about ampersands in gravatar URLs
Support for /my/preferences to automatically redirect to the logged in
user.
fixing the composer that I just re-broke
Merge pull request #2286 from awesomerobot/master

fixing the composer that I just re-broke
copyedits on editor entry errors
make top user link profile, not activity
minor digest email copyedits
improve test email error message
BUGFIX: add h2 with period when browsing top pages
BUGFIX: only redirect users top /top page once
clarify register account
better first boot register admin account help
Update INSTALL-digital-ocean.md
incorrect image urls in guide
TRIVIAL: remove puts statement (cc. @eviltrout)
Add a SiteSetting to configure how many topics are in the email digest.
FIX: Link to user profile broke the back button
BUGFIX: if SSO is enabled invite system is disabled