Add SlickGrid.
Fixed versions of jquery.event.{drag, drop}.

These are SlickGrid prerequisites.  Sprockets expects them to be encoded
in UTF-8, but the versions that ship with SlickGrid have a byte sequence
that's illegal in UTF-8.  The fix: iconv them.
SlickGrid include files.
Add a grid to Pancakes' event search view.
Switch to PostgreSQL for development and test.

I was starting to hit locking problems with SQLite when running lots of
jobs to e.g. stress-test the search worker.
Use PostgreSQL in CI.