Add 'content top' and 'content bottom' regions

Issue Link: 
http://drupal.org/node/428744
criticality: 
Moderate
Drupal7: 
Fixed
Task: 
Post some example content
This happened to: 
Participant 1

User added block to the header region attempting to add a block directly above the content.

Trying to put a block above content.

Solution: 
Add a content bottom and content top regions to all core themes.