Add a slider UI directive (encapsulating jquery.nouislider) to control
the date range on the test run summary plot graph.

Refactor the plot summary graph rendering and associated controlled to
get away from using timeouts to control the UI clogging. We now buffer
the data in the controller until it is fully loaded before notifying the
UI.

The slider directive now has the sole responsibilty for triggering
recent test run summary data loads.

One more thing, added a placeholder in the summary graph directive for
capturing  ctrl + click events. These will be used for compare
functionality in later commits.