Update OSM installer to allow an external IP address for the cluster

Change-Id: Ic760f427dddbaf50532c87074834585b4674cd7e
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>
Signed-off-by: ramonsalguer <javier.ramon@telefonica.com>
diff --git a/installers/install_osm.sh b/installers/install_osm.sh
index ba116cc..622ff36 100755
--- a/installers/install_osm.sh
+++ b/installers/install_osm.sh
@@ -135,7 +135,7 @@
     [ -z "${DEBUG_INSTALL}" ] || DEBUG end of function
 }
 
-while getopts ":a:c:r:n:k:u:R:D:o:O:N:H:S:s:t:U:P:A:l:L:K:d:p:T:f:F:G:M:-: hy" o; do
+while getopts ":a:c:e:r:n:k:u:R:D:o:O:N:H:S:s:t:U:P:A:l:L:K:d:p:T:f:F:G:M:-: hy" o; do
 
     case "${o}" in
         D)