FLUME-299: Add support for subarguments in flume config elements
Review Request #1757 - Created May 21, 2011 and submitted
This updates the grammar to support "functions" with subargs. Initial goal is support compression sub-arguments to avro/seqfile, but will also be used for roll triggers and other things in the future. This is related to flume-420, with the end goal of supporting flume-632.
test run and pass.