Revert "remove gfs"

This reverts commit ee07614ffbc7127dc9dd4f57b072a412e4d75b16.
add glusterfs configuration setting info
switch glusterfs repo to sonatype
fix line length
enable glusterfs unit test profile
add glusterfs minicluster test
add hadoop-client v2 as glusterfs test dependency
if host doesn't have a glusterfs mount point, let gluster cluster test fall to local filesystem cluster
relocate gluster mount point to /tmp to allow non-root to create a local fs cluster
restructure pom.xml, not to spill glusterfs-only parameters to other profiles
replace dependent hadoop artifact
remove test related parameters from pom.xml
document missing glusterfs parameter
in unit test, make gluster mount point command line param
update instruction to run glusterfs unit tests
Merge pull request #215 from rootfs/glusterfs-merge

Restore Glusterfs with update