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
New pie wedgeEventsEnable/Disable implementations

- The wedgeEventsEnable and wedgeEventsDisable methods now increment and
  decrement a counter.  When the counter is 0, mouse events are enabled,
  otherwise they are disabled.  As a result, multiple calls to
  wedgeEventsDisable require a matching number of calls to
  wedgeEventsEnable to turn wedge mouse events back on.  This is useful if
  multiple animations will happen in succession and the goal is to
  disable mouse througouth the entire transaction.
- Simplified generateId method in core.