buffering writes
Allow write buffer size as a parameter from hadoop/core-site.xml.

to adjust java write buffer,  specify fs.glusterfs.write.buffer.size in core-site.xml in bytes.
conf.xml example + added test for buffering of Fuse stream
update test to exactly confirm 2 bytes post flush
Merge pull request #26 from gluster/buffering_writes

Configurable buffered writes in memory.