clean up the /frequent_unsuccessful_level_sources page (the hint list interface)
retry on duplicate usernames; also generate usernames in teacher dashboard
forgot file
Merge pull request #226 from code-dot-org/hint-ui

clean up the /frequent_unsuccessful_level_sources page (the hint list in...
Merge pull request #229 from code-dot-org/username-fixes

Username fixes
Merge pull request #230 from code-dot-org/staging

DTT