Draft of Alpha release announcement

All:

This goes out Thursday, so I'm putting it here for final
comments/corrections.  Sorry for the last-minute nature of this, but
time kind of got away from me.

I've added a new "what to test" section to get people thinking.  We
should create a more expanded version of this on the wiki for 9.5beta1,
but for now, what do people think?

--
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com