Added Canned Responses to the Bug Status dialog

Added preset responses to the bug status dialog that will automatically
append a comment when selected.
The bug status dialog now works with multiple bugs selected.
The event pane is now being cleared when multiple bugs are selected
More preparations for "diff"ing
Neo4jBugGraphImpl will no longer save empty comments or null statuses.
Added the Duplicate value to the Status enum so selecting that value
will no longer throw an exception.