web: Added case to updateCircle: check for expiration date coming from
the client as a MM/dd/yyyy string.  

Sending the exipiration date as a millis value produced a problem: the
date on the server was different from the date passed by the client,
because the client and server were in different time zones.  So if the
client passed a millis representation of 12/25/13 12:00am, the date
saved on the server would be 12/24/13 10:00pm