No more return false from onBeforeClose

You can no longer return false from onBeforeClose to prevent a view
from closing. This behavior was inconsistent with the rest of the
library, and would require far too much logic to respect in all cases.
Instead of returning false, you should handle your logic *before*
calling close on the view.
Adds before:child:remove to collectionView

- Adds before:child:remove to collectionView
- Adds tests for child:remove and before:child:remove
- Only triggers child:remove when a child is removed
compositeview onChildAdd binding
abstract the regionManager lookup into a helper.
add banner image to readme
Readme cleanups
Merge pull request #1214 from marionettejs/sjs/readme-fixes

Readme cleanups
install from bower on build

fixes #1182
Merge pull request #1209 from ahumphreys87/compositeAddChild

compositeview onChildAdd binding