9.5 commit fest schedule

For those who were not at the developer meeting, here is the commit fest
schedule for 9.5:

June 15
August 15
October 15
December 15
February 15

beta in June 2015

The obvious change is that there will be five commit fests instead of
four.  Also, the time between beta and release is planned to be a bit
shorter.

The first commit fest will continue to use the existing web app
(https://commitfest.postgresql.org/action/commitfest_view?id=22), while
the new one continues to be developed.

We need a volunteer to manage the first commit fest.