This adds Twitter and Facebook sharing using the "Build your own Tweet button"
and Share Dialog methods, respectively. Both are javascript and iframe free;
instead you link to a specified url. For Twitter customization arguments
are sent through query parameters. Facebook requires you to put open graph
meta tags at the shared url.

Right now the user has to ensure their badge is made public before sharing.
Nothing stops you from sharing a private badge, but that link will be broken
when people try to visit it.
Move template off items
Attach shareTokens to badge objects for backpack.html page, and use correct share url for social sharing
Fix share url
Change from single share modal to one share modal per badge
Add ajax public/private toggle to badge share modal
Disable social network share buttons for private badges, and add explanatory text
Update facebook open graph share metadata
Removing legacy template `user` objects
Adding 'search' to `/earn` and `/explore` filters

Resolves #616
Fixing `getBadges` test to allow for `search`
Merge pull request #663 from andrewhayward/search

Adding 'search' to `/earn` and `/explore` filters
Merge pull request #662 from andrewhayward/tweaks

Removing legacy template `user` objects
Moving notification to global scope

Underage learners without guardians now get a message on every page
removed favorite buttons. fixes #665
added privacy policy page copy. added link to privacy page for guradian signup. changed link in footer to point to privacy page and linked to pdf from privacy policy page. fixes #628
Change explanatory text around making badges public in share modal
Tidy up share styles slightly
DRY out template a bit with a macro
adds search and many other fixes. also corrects bug in env variables where under 13 'email' was malformed. doesn't include social or iremix. production release