Fix p4vm script to export ova and tutorial script

- Modify missing command in tutorial-bootstrap.sh
- Modify command order in ova-cleanup.sh
- Modify the way to execute ovs-cleanup.sh in vm

Change-Id: Ib010d07b31d9b06f3c4b04d34b2036c0058ca300
(cherry picked from commit f1a04004363d2c59108ad3ca9277c09ec1a2167a)
diff --git a/tools/dev/p4vm/tutorial-bootstrap.sh b/tools/dev/p4vm/tutorial-bootstrap.sh
index eb38786..1c7b566 100755
--- a/tools/dev/p4vm/tutorial-bootstrap.sh
+++ b/tools/dev/p4vm/tutorial-bootstrap.sh
@@ -9,10 +9,10 @@
 echo "lightdm shared/default-x-display-manager select lightdm" | debconf-set-selections
 
 # Install ubuntu desktop from tasksel
-apt-get -y --no-install-recommends tasksel
-tasksel ubuntu-desktop
+apt-get install -y --no-install-recommends tasksel
+DEBIAN_FRONTEND=noninteractive tasksel install ubuntu-desktop
 # Remove gnome, install unity
-apt-get remove gdm3 ubuntu-desktop
+apt-get remove -y gdm3 ubuntu-desktop
 DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
     ubuntu-unity-desktop lightdm \
     gnome-panel \
@@ -27,4 +27,4 @@
 
 DEBIAN_FRONTEND=noninteractive apt-get -y install wireshark
 echo "wireshark-common wireshark-common/install-setuid boolean true" | debconf-set-selections
-DEBIAN_FRONTEND=noninteractive dpkg-reconfigure wireshark-common
\ No newline at end of file
+DEBIAN_FRONTEND=noninteractive dpkg-reconfigure wireshark-common