Bind to events only when the picker is shown.

Greatly increases performance on slow machines with IE8 when multiple
datepickers have been instantiated.
Fixes a memory leak.
Differentiate between main events (needed at picker init) and secondary events (only needed when picker is open)
Build event handler lists at init, not every time we attachEvents
Begin release 1.0.2-rc.2
Update changelog
Update component.js version
Added tag 1.0.2-rc.2 for changeset f6211e251c02
Release version 1.0.2
Added tag 1.0.2 for changeset 493d2332f0cb