Fix vagrant scripts to add IPv6 correctly

The script did not use the sudo command correctly, thus not really
enabling the IPv6 support.
Also, Moved the commands to the common script rather than having it
duplicated in all the scripts.

Change-Id: I66e84d76d905584635d42997f41eaef9d0263d3c

vagrant/provisioning/setup-aio.sh

@@ -22,8 +22,4 @@ SERVICE_HOST_NAME=\${HOSTNAME}
 SERVICE_HOST=$ipaddress
 DEVSTACKEOF
 
-# Patch to enable IPv6
-sudo sysctl -w net.ipv6.conf.all.disable_ipv6=0
-sudo echo "net.ipv6.conf.all.disable_ipv6 = 0" >> /etc/sysctl.conf
-
 ~/devstack/stack.sh

vagrant/provisioning/setup-base.sh

@@ -16,3 +16,7 @@ fi
 if [ ! -d "dragonflow" ]; then
     git clone https://git.openstack.org/openstack/dragonflow.git
 fi
+
+# Patch to enable IPv6
+sudo sysctl -w net.ipv6.conf.all.disable_ipv6=0
+sudo sh -c 'echo "net.ipv6.conf.all.disable_ipv6 = 0" >> /etc/sysctl.conf'

vagrant/provisioning/setup-compute.sh

@@ -18,8 +18,4 @@ cat << DEVSTACKEOF >> devstack/local.conf
 HOSTNAME=$(hostname)
 DEVSTACKEOF
 
-# Patch to enable IPv6
-sudo sysctl -w net.ipv6.conf.all.disable_ipv6=0
-sudo echo "net.ipv6.conf.all.disable_ipv6 = 0" >> /etc/sysctl.conf
-
 ~/devstack/stack.sh

vagrant/provisioning/setup-controller.sh

@@ -23,8 +23,4 @@ SERVICE_HOST_NAME=${HOSTNAME}
 SERVICE_HOST=$ipaddress
 DEVSTACKEOF
 
-# Patch to enable IPv6
-sudo sysctl -w net.ipv6.conf.all.disable_ipv6=0
-sudo echo "net.ipv6.conf.all.disable_ipv6 = 0" >> /etc/sysctl.conf
-
 ~/devstack/stack.sh