Start work on favorites

Implemented:

 - DB model
 - Add badge to favorites view
Minor
Favorite from badge detail
Link back to badge after favoriting
Refactor favoriting a badge to class method
1st pass at favorites middleware for badge lists
Merge in from master
Fix bug in favorites middleware with async

This also renames the flag on the badge from "favorited" to "favd"
Move favorited status/button to badge thumbnail
Minor refactor
Favorites middleware creates list of fav'd badges

This changes the favorites middleware to, in addition to adding a "favd" flag
property on each user's badge, add a list of the user's favorited badges to
the `req' object.
Initial /myplaylist view
Add menu item to /myplaylist
First pass at playlist model
Refactor playlist view
Ability to add badges to playlist & display them

The basic functionality works, but the key missing piece is that the
*getBadges* API call to openbadger, as exposed in the openbadger.js module,
doesn't return all badges, which we need to filter down on.

The next step is to add another middleware function that returns **all** of
the badges from openbadger.
Add `getAllBadges' variant to API wrapper

The `getBadges' API call in the openbadger module returns a paginated array of
badges, but for certain functions -- like filtering down the playlist or
favorites -- we need access to all the badge objects at once.
Remove console.log statements
Switch playlist to use new getAllBadges call
remove footer top border and add some margin around mozilla logo