Cleaned up event teasers.  #1637

Deviated from the original ticket a little.  It removes the date from events, but only if they take place on one day.  A week long conference shows the date range.

Removed end date if it's the same as start date.  4pm-4pm is silly.
Merge branch 'SCHOLAR-3.x' of github.com:openscholar/openscholar into SCHOLAR-3.x