edx/edx-platform — pull request #1738 by polesye (2013-11-21 12:46:38+00:00)
Title: Update the calculator hints tooltip with full information.

In this PR is updated the calculator hints tooltip with full information.
Also are updated a11y things: navigation by tabbing is replaced by `aria-labeledby` attribute. Pressing ESC button close opened hint.

Ticket: [BLD-400](https://edx-wiki.atlassian.net/browse/BLD-400).

@jmclaus please review.