[front-end] add modal window for widget addition
[front-end] add style for modal windol of widget addition
[front-end] add modal window and controller for window addition form
[front-end, bugfix] fix page deletion
[front-end, docs] Write docs for most widgetApi stuff.

Use prototype-based methods in APIProvider, APIUser, EventPublisher
[front-end] add noicon:true property where needed
[front-end] add widget icons
[front-end] add default icon for all widgets with no icon
[front-end] add icon column to widget addition modal
[front-end] add paths to icon images for each widget in widget addition modal scope
[front-end] add styles to show widget icons in widget addition modal
[front-end] move SCEditor bug-fix hack out of controller
[front-end] highlight selected table row
[front-end] add selected table row style
[front-end] change class of a selected item fynamically
[front-end] add widget icon to appUrls service and remove unnecessary dependency
[front-end] remove extension from constant
[front-end, bugfix] change accessed constant name
[front-end] get propery by . operator
[front-end] remove hard-coded css class from controller using ng-class