Case list/detail page redesign

[Ticket](http://manage.dimagi.com/default.asp?138199) / [Spec](https://docs.google.com/a/dimagi.com/document/d/1c69akYecY0SqUzuWUg_25gudELWh509vpgdHaRfgCHA/edit)

Various changes to the case list/detail page. Case list and case detail are now in separate tabs. Add properties with a drop down menu. Case list filters now in a single text field.

Note that this requires a migration that will be run on every app. I plan on PRing a separate migration to destroy the `DetailColumn.filter_xpath` fields once we are satisfied that this transition has gone smoothly.
This is not safe: http://stackoverflow.com/a/8186110/10840

Change to `filter != ()`