Fix posts select all function - use .prop() not .attr()

For more info see:
http://ejohn.org/blog/jquery-16-and-attr/
http://stackoverflow.com/questions/5874652/prop-vs-attr
Add notification for success/failure when bulk unpublishing/published posts
Add confirmation dialog, and notifications when bulk deleting posts
Clean up formatting of chained calls in PostItemView
Add @todo