template: A minimal example xlator to build on

This xlator is intended to save new GlusterFS developers
from fighting it with autotools.

How to add template xl onto the xlator graph?
[..]

volname-template
type testing/features/template
subvolumes volname-dht
end-volume

[..]

Change-Id: If513284bb590be7c3b093054108dba2883064190
BUG: 916985
Signed-off-by: Krishnan Parthasarathi <kparthas@redhat.com>
Reviewed-on: http://review.gluster.org/4604
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>