Refactor render scheduling

[emartinez-usgs]

Use individual event handlers on change:property events from the model that enable a renderScheduled flag. The basic change event from the model is bound to render which checks if renderScheduled is true and, if so, rendering proceeds.

Some known places where this needs to be implemented.

• GenericCollectionView
• CheckboxOptionsView
• RadioOptionsView
• ListView
• ModesView

[emartinez-usgs]

I did some work on this and pushed it to my origin under a branch called "issue-196". You can use this as a starting place. Currently, this branch deals with the generic collection view, radio/checkbox views, and started on the list view. The map view could be done in isolation.