The javascript is very inconsistent between pages. I'm trying to
start using a consistent pattern where the api call is kept in a
separate function from the ones that buttons and input boxes
talk to.
Instead of embedding the entire tag list in the search.html template
every single time, this script loads the tags from the new,
cache-enabled endpoint /all_tags.json. Then we can use html5
datalists to create autocomplete forms on the search and photo pages.
