Backbone: further refactored funcionality out into Backbone prototype extensions...

... and fixed menu dropdown bug.
Backbone: fix no navigation away on list deletion bug.
Backbone: Remove todo items...

noticed that the list title update but is gone (where if viewing list
the title was not updating in show view when editing in the sidebar).
Did not deliberately fix this. Interesting to figure out the cause.
Backbone: Fix bug where unsaved lists / tasks were rendered.
Backbone / JS: add JQuery UI, implement V1 priority slider for tasks...

Slider implementation needs improvement!
Styling: Add icon font for site icons. Add drop down menu icons.
Style: further refine task priority form drop down.