Normalize timepicker events

Previously events were used to to trigger methods on
the timepicker. Binding to open.timepicker would result in
too many calls.

This change replaces events with function calls and adds
an onOpen event which is only triggered when the picker is
actually opened.

Similarly for the onSelect event.
Update README.md with event info
Return the timepicker constructor
Use spy instead of fired
Use single tick quote
Replace isOpen state with DOM check
Merge pull request #11 from jdelight/normalize-events

Normalize events