PIG-3131: Document PluckTuple UDF (rjurney via jcoveney)

git-svn-id: https://svn.apache.org/repos/asf/pig/trunk@1447712 13f79535-47bb-0310-9956-ffa450edef68
PIG-3191: [piggybank] MultiStorage output filenames are not sortable (Danny Antonelli via jcoveney)

git-svn-id: https://svn.apache.org/repos/asf/pig/trunk@1447727 13f79535-47bb-0310-9956-ffa450edef68
Merge remote-tracking branch 'remotes/apache/trunk' into trunk
Adds a test extracting subset of fields