PIG-3332: Upgrade Avro dependency to 1.7.4 (nielsbasjes via cheolsoo)


git-svn-id: https://svn.apache.org/repos/asf/pig/trunk@1484990 13f79535-47bb-0310-9956-ffa450edef68
PIG-3297: Avro files with stringType set to String cannot be read by the AvroStorage LoadFunc (nielsbasjes via cheolsoo)


git-svn-id: https://svn.apache.org/repos/asf/pig/trunk@1484997 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/trunk' into trunk