Rewrite README in RST

Change-Id: Ia0a51a4d971e5bb74555cdf6fb316f31e389b48b
Reviewed-on: http://review.couchbase.org/27056
Tested-by: Mordechai Nunberg <mnunberg@haskalah.org>
Reviewed-by: Matt Ingenthron <matt@couchbase.com>