Jhbate/edit delete

@kentquirk here is the outlined I promised. Fire away :)

### Changes to allow for edit and delete end points
 - config added for the deleteWindow
 - mongo client implements edit and delete functions and filters out messages flagged for deletion from being return 
 - message-api now include edit and delete, other methods documented for better readability 
- tests update for edit and deletion cases
- mongoHandler tests expanded to ensure we only bring back message that have not been flagged for deletion

### To consider 
 - should we now store a created and updated timestamp for messages
 - the clean task that deletes messages should also look for orphaned messages (i.e. the root message or note is deleted do we also remove any replies to that message as part of the cleanup)
- opps - I didn't mean to delete that. Do we allow an undo