Prepare for 1.7.3-rc2: updated projected release date.

git-svn-id: https://svn.apache.org/repos/asf/avro/trunk@1416598 13f79535-47bb-0310-9956-ffa450edef68
Prepare trunk for 1.7.4 development.

git-svn-id: https://svn.apache.org/repos/asf/avro/trunk@1418496 13f79535-47bb-0310-9956-ffa450edef68
AVRO-1217. Python: set_meta on DataFileWriter does not do anything

git-svn-id: https://svn.apache.org/repos/asf/avro/trunk@1418584 13f79535-47bb-0310-9956-ffa450edef68
AVRO-1211. Add MR guide to documentation. Contributed by Skye Wanderman-Milne.

git-svn-id: https://svn.apache.org/repos/asf/avro/trunk@1424014 13f79535-47bb-0310-9956-ffa450edef68
AVRO-1221. Java: Fix TestSaslDigestMd5 to pass on IBM JVM.  Contributed by Rodrigo Trujillo.

git-svn-id: https://svn.apache.org/repos/asf/avro/trunk@1424223 13f79535-47bb-0310-9956-ffa450edef68
AVRO-1008. Java: Improve support for forcing connection handshakes.

git-svn-id: https://svn.apache.org/repos/asf/avro/trunk@1424699 13f79535-47bb-0310-9956-ffa450edef68