AVRO-1471. Java: Permit writing generated code in different character encodings.  Contributed by Eugene Mustaphin.

git-svn-id: https://svn.apache.org/repos/asf/avro/trunk@1577670 13f79535-47bb-0310-9956-ffa450edef68
AVRO-1482. In specification, place null first in unions as best practice.

git-svn-id: https://svn.apache.org/repos/asf/avro/trunk@1577673 13f79535-47bb-0310-9956-ffa450edef68