Add areas selection to business support editions

https://www.pivotaltracker.com/story/show/64389738
Adds a panopticon-style 'select2' multiple search/select field to associate Imminence areas with a BusinessSupportEdition.
![screenshot - 250614 - 11 22 33](https://cloud.githubusercontent.com/assets/93511/3383993/a673dce8-fc52-11e3-99ba-5a0c3301dac6.png)


It's generally safer to use `.prop('checked', false)` instead of manipulating the "checked" attribute.