UX - Updated date formatting [MJ-362]

This took longer than it should have, mostly due to how oddly our ProfileUnit class works.

The main addition of this pull request is a new template tag that reduces potential duplicated code in myprofile templates and makes it easier to pretty-print model fields based on field type.

All dates now appear using the same format, including values produced by the jQuery UI datepicker.

LocaleMiddleware isn't strictly necessary to accomplish this, but it will at least produce something more easily recognizable than the previous 'yyyy-mm-dd' if dates are mishandled in the future. It will also make future L10N efforts easier.

The broken saved search qunit test is fixed in #232 and the broken profile qunit tests are covered by an existing ticket. Other than that, all tests pass.