Add admin-only upload file interface

Untested.  File upload error case is also still broken.
Fix Asset.formForFile in a partly better way
Upgrade to play 2.1.5
Allow admins to override format detection for uploads, too
Beware of where clauses on outer-joined tables

Fixes assembla-135
Secure deploy's prod.conf.example
Use extension for fallback detection on upload
Merge remote-tracking branch 'remotes/origin/master' into gui
Add container fields to full slot edit page

Left container edit page in place for now.  Closes assembla-132
Merge remote-tracking branch 'remotes/origin/master' into gui
remove containers from user view; streamlined editing records from the slot edit form.