fix #523 ellipsis bug fix + unit test

bug in the ellipsis element:
add an optinal property in aria text and sortindicator to compute the width that
prevents the text to get clipped.
feat #574 HTML select widget

The select widget has 3 properties:
- a list of 'options' to populate the select element
The user can bind to his data model:
- 'selectedIndex'
- 'value'

close #574
fix #605 HTML select widget: the 'value' property isn't properly bound

When binding only the value property of the html select widget, the
selected value was not correctly restored after refresh.
fix #609 Updating grunt to fix underscore.string issue with npm install

Grunt was relying on underscore.string version 2.2.0rc, but the version
number was renamed on npm to 2.2.0-rc (with the dash), which breaks
compatibility.
fix #610 Robot-related regression in IE8

Close #613