Replaced some apt calls by apt-get calls

Change-Id: Ia9d4f7d60bbcf6d730e0b0cfc802728ed9d23a9d
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>
diff --git a/jenkins/osmclient/start_build b/jenkins/osmclient/start_build
index 2206a1a..155fefa 100755
--- a/jenkins/osmclient/start_build
+++ b/jenkins/osmclient/start_build
@@ -34,8 +34,8 @@
 
 OSM_git_checkout "$@"
 
-apt update
-apt install -y docker.io
+apt-get update
+apt-get install -y docker.io
 
 # cleanup all pre-existing builds.
 # deb pkg build fails if previous build image is present