Fixed:
#570074 'Access denied' when trying to edit a revision
Changes:
-No longer require administer nodes to use
-Moved Save as Draft checkbox so always visible
-Added and updated messages to be more useful
-Smart display of actions you are able to perform when viewing a draft revision, based on permissions
*Now automatically enables revision if Save as Draft checked
*Disabled Save as Draft checkbox on node creation form
*Cleaned code to pass Coder module checks