glusterd/geo-rep: Use getent passwd instead of $HOME

$HOME might not be set in the env variables, as is the case
when these scripts are executed using the runner framework.
Hence using getent passwd instead of $HOME

Change-Id: I99f6bcd788d727be534b3040600d66c8dbb7ee92
BUG: 1099041
Signed-off-by: Avra Sengupta <asengupt@redhat.com>
Reviewed-on: http://review.gluster.org/7803
Reviewed-by: Atin Mukherjee <amukherj@redhat.com>
Reviewed-by: Kotresh HR <khiremat@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Venky Shankar <vshankar@redhat.com>
Tested-by: Venky Shankar <vshankar@redhat.com>