horizontal scroll mixin
Adding horizontal scrolling button and generic support.
Take back some code from SCiMap.
Create new mixin.
Allow columns to adapt to size using grid auto-fit.
initial tests
Prevent auto fit from executing
Prevent scrollbar overlap
Styling button
Set table-layout to auto to allow correct widths to be calculated.
Refactor to use AutoFit view rather than mixing for UI
Refactor column chooser to an Ember view with appropriate bindings.
Refactor column chooser to use Ember view/template
Merge pull request #275 from PrimeRevenue/feature/horizontal_scroll_button

Feature/horizontal scroll button