Add a thumbnail view to the /media_assets page. This page lets you see
all images uploaded to Danbooru by all users (although you can't see who
the uploader is). Also add a link to this page in the subnav bar on the
upload page.
Previously the search form on the /iqdb_queries page submitted directly
to the iqdb service (karasuma.donmai.us), which redirected back to
Danbooru with the search results.
This was different than API requests, which submitted to
/iqdb_queries.json which proxied the call to iqdb through Danbooru.
Because of this, searches on the /iqdb_queries page had different
behavior than API requests. Things like filesize limits and referrer
spoofing were handled differently.
Now searches on the /iqdb_queries page submit directly to Danbooru. This
is simpler and it means that API requests and HTML requests have the
same behavior.
