Update JS libraries

jQuery, Underscore, Backbone etc.
Refactor localStorage

Change localStorage calls to a new abstracted class that emits events
that can be caught. Breaks compatibility with older lfa-private-addons
Backstage and Exercises
Small typo fix
Added sidebar open/close event
Merge pull request #111 from dapetcu21/master

Added sidebar open/close event
Chapter jades are now only run at compile time
Merge pull request #112 from dapetcu21/master

Chapter jades are now only run at compile time
Made menu items more general purpose
Unselectable menu buttons
Merge pull request #113 from dapetcu21/master

General purpose menu items
Fixed scroll locking on textbooks with no browser detection
Merge pull request #114 from dapetcu21/master

Fixed scroll locking on textbooks with no browser detection
Added ready event
Merge pull request #115 from dapetcu21/master

Added ready event
Keyboard navigation
Fixed hang on loading issue
Updated backbone
Merge pull request #116 from dapetcu21/master

Last minute work for Frankfürt
Bumped version
Merge branch 'master' of github.com:learnfwd/lfa