isMousePath/Element fix and animateJQP enhancement

core.js
* isMouseInPath and isMouseInElement previously broke if the location of
  the Elroi element changed; this was a result of the element offset
  being cached. The offset is now determined dynamically using the
  getRelativeMousePosition method.
* Added stopJQP method which provides a way to stop an element and reject
  the promise generated by animateJQP.  Previously if animateJQP wasused
  the promise it returned would remain in limbo if a call to stop()
  was made.
Merge pull request #9 from gsmith85/promise-fix-and-mouse-in-path-fix

isMousePath/Element fix and animateJQP enhancement
y label formatting controlled by function that can be reset via options.  Allowing
backwards compatibility.
Merge pull request #10 from ahahn/master

customizable y-axis label formatting
README clean up

- Removed extraneous 'http://'
- Capitalized Elroi in all cases other than in the filename elroi.js