Bootstrap

This is not ready to merge yet - I want to see all the issues not marked low priority in the Bootstrap milestone done first. Creating the PR for easier code reviewing and so I can make the list below (I like lists).

I've tried to keep this as client side as possible, but unfortunately that didn't work - in some cases server-side changes were necessary, in others I may have forgotten...

Changes in a nutshell:
- Removes some more leftover version broker code
- Replaces the general page template layout with Bootstrap
- Replaces jQueryUI icons with Bootstrap icons
- Replaces jQueryUI state-highlight and helper-hiddens with Bootstrap alerts and hiddens
- Replaces jQueryUI Slider on Show Planner with a home-grown slider
-- Adds support for viewing the intro on a track
-- Adds support for setting a cue point on a track
- Replaces jQueryUI datetimepicker plugin with Bootstrap-based picker
- Replaces jQueryUI autocompletes with typeahead.js (and Bloodhound)
-- Lots of potential to do more cool stuff here later
- Replaces jQueryUI dialogs with myury.createDialog function
-- Ajax requests now serve a 401 when a login is required
-- Global ajax handler now responds to 401s by redirecting the user to the login page
- Replaces jQuery contextmenu plugin with home-made context menu that uses Bootstrap
-- Fixes Show Planner Automatic Advance/Play On Load functionality
-- Adds support for the Repeat options in Show Planner
-- Adds support for deleting items using the context menu in Show Planner
- Replaces jQueryUI's js file with one that just contains the Sortable plugin (now much lighter!)
- Moves datatables away from jQueryUI plugin, uses Bootstrap styles instead
- General polish to the Show Planner upload functionality
- Adds Moment.js (currently only loaded in forms)
- Fixes some requests being POSTs where GETs are sufficient