Add month and day to the "Updated At" label on a graph widget.

We are pulling a large number of metrics from slow/flakey data sources and the "Updated At hour:minute" label on graphs is not sufficient for us to know that something has gone wrong. We may only get a few updates a day and so when something goes wrong it can be days before we notice (based only on the time stamp).  By making the label "Updated At hour:minute on month/day" we notice data retrieval issues much more quickly. 

Thought this might be useful for others...