Appdb - Add 'Delete' button to comments when the user is an admin

[Chris Morgan]

This patch adds a delete button to comments when the user is an admin.  It 
will need to be modified slightly when application maintainers are added to 
appdb.  The hope is that we can start to clear the stale comments out of the 
database to increase the signal-to-noise.

After deleting the comment the parentId of the child comments are adjusted to 
be the parentId of the deleted comment.

I'm still a php rookie, comments, questions are welcome ;-)

Chris