Fix: The vim-emu installation requires OVS to be installed

on the host machine. This wasn't an issue before because OVS
was automatically installed as part of some other installation
procedures. Now, OVS is not 'automatically there' and will
cause vim-emu to not work properly after the installation.

Change-Id: I562bc83ee21e18bf35a175e81f900b2d2ee3fd59
Signed-off-by: peusterm <manuel.peuster@uni-paderborn.de>

installers/full_install_osm.sh

@@ -1338,6 +1338,8 @@ function install_vimemu() {
     echo "\nInstalling vim-emu"
     EMUTEMPDIR="$(mktemp -d -q --tmpdir "installosmvimemu.XXXXXX")"
     trap 'rm -rf "${EMUTEMPDIR}"' EXIT
+    # install prerequisites (OVS is a must for the emulator to work)
+    sudo apt-get install openvswitch-switch
     # clone vim-emu repository (attention: branch is currently master only)
     echo "Cloning vim-emu repository ..."
     git clone https://osm.etsi.org/gerrit/osm/vim-emu.git $EMUTEMPDIR