Fix DST issue in SensingPrims.primTimestamp.
Use toBeCloseTo for javascript numbers.

5280 is the precise number of days between these two dates
as currently implemented.

Between
  1st of Jan 2000 23:59 and 16th of June 2014 00:00 -> 5280
  1st of Jan 2000 00:00 and 16th of June 2014 23:59 -> 5281.999...8

Related to issue #54.
Extend .is(:focus) check to activeElement.

If this test has to be used more often, I suggest to use a prototype.

This bugfix is based on various SO threads like
  http://stackoverflow.com/questions/18850219/testing-for-focus-an-angularjs-directive
Merge pull request #55 from prokls/prokls/activeElement

Check focus using document.activeElement
Merge pull request #54 from prokls/master

SensingPrims.primTimestamp and Daylight Savings Time
Merge from upstream