Finish the doc for developers

* Added package installation section
* Cleaned up functional test setup

Change-Id: I3ead97408a33daed8a9b430ef6b6569036f1e025
Signed-off-by: Luis Pabon <lpabon@redhat.com>
Reviewed-on: http://review.gluster.org/5438
Reviewed-by: Kyle Schneider <kinnder@gmail.com>