Cross-platform changes to onos.initd

We now can use start-stop-daemon (debian), daemon()
shell function (centos), or sudo (others) to start
onos-service.

It should be backward compatible on systemd systems.

Tested on Ubuntu 14 and CentOS 6. Should also work on
Ubuntu 15/16, CentOS 7, Debian, and Fedora.

(Note that we should test this against various OSes,
preferably automatically rather than manually!)

Addresses at least part of ONOS-2907

Change-Id: I4ded98baf02321a5a9db37fdff19e1ce4a3d23d2
diff --git a/tools/test/bin/onos-install b/tools/test/bin/onos-install
index f0fb9dd..e35585c 100755
--- a/tools/test/bin/onos-install
+++ b/tools/test/bin/onos-install
@@ -55,7 +55,7 @@
 
 [ ! -z "$mvn_settings" ] && scp -q $mvn_settings $remote:/tmp/settings.xml
 
-ssh $remote "
+ssh -tt $remote "
     [ -d $ONOS_INSTALL_DIR/bin ] && echo \"ONOS is already installed\" && exit 1
 
     # Prepare a landing zone and unroll the bits