Show achievements on the user profile page

Makes a few key changes to the way achievements will end up working:
 - Rather than store achievement definitions in the DB, they're stored as a static list in code.  A few sample achievement definitions were added.
 - Achievements were moved into the user app, and the `achievement` app was renamed to `quiz`

Also fixes an issue with the gulpfile image copying (which I noticed after I added our first image).
Rather than deleting the migration, should we, instead, create a second migration to delete the, now orphaned, ``achievement_achievement`` and ``achievement_ achievementdefinition`` tables?