Add an option to skip IKEv2 setup

- Add an option to skip IKEv2 setup when installing the IPsec VPN.
  Example: sudo VPN_SKIP_IKEV2=yes sh vpn.sh
- This allows users to set up an IKEv1-only VPN, or install IKEv2
  interactively using "sudo ikev2.sh" after VPN setup.

extras/quickstart.sh

@@ -273,6 +273,7 @@ run_setup() {
       VPN_DNS_SRV1="$VPN_DNS_SRV1" VPN_DNS_SRV2="$VPN_DNS_SRV2" \
       VPN_DNS_NAME="$VPN_DNS_NAME" VPN_CLIENT_NAME="$VPN_CLIENT_NAME" \
       VPN_PROTECT_CONFIG="$VPN_PROTECT_CONFIG" \
+      VPN_SKIP_IKEV2="$VPN_SKIP_IKEV2" \
       /bin/bash "$tmpdir/vpn.sh" || status=1
     else
       status=1

vpnsetup.sh

@@ -273,6 +273,7 @@ run_setup() {
       VPN_DNS_SRV1="$VPN_DNS_SRV1" VPN_DNS_SRV2="$VPN_DNS_SRV2" \
       VPN_DNS_NAME="$VPN_DNS_NAME" VPN_CLIENT_NAME="$VPN_CLIENT_NAME" \
       VPN_PROTECT_CONFIG="$VPN_PROTECT_CONFIG" \
+      VPN_SKIP_IKEV2="$VPN_SKIP_IKEV2" \
       /bin/bash "$tmpdir/vpn.sh" || status=1
     else
       status=1

vpnsetup_alpine.sh

@@ -538,12 +538,20 @@ EOF
 set_up_ikev2() {
   status=0
   if [ -s /opt/src/ikev2.sh ] && [ ! -f /etc/ipsec.d/ikev2.conf ]; then
+    skip_ikev2=0
+    case $VPN_SKIP_IKEV2 in
+      [yY][eE][sS])
+        skip_ikev2=1
+        ;;
+    esac
+    if [ "$skip_ikev2" = "0" ]; then
       sleep 1
       VPN_DNS_NAME="$VPN_DNS_NAME" VPN_PUBLIC_IP="$public_ip" \
       VPN_CLIENT_NAME="$VPN_CLIENT_NAME" VPN_XAUTH_POOL="$VPN_XAUTH_POOL" \
       VPN_DNS_SRV1="$VPN_DNS_SRV1" VPN_DNS_SRV2="$VPN_DNS_SRV2" \
       VPN_PROTECT_CONFIG="$VPN_PROTECT_CONFIG" \
       /bin/bash /opt/src/ikev2.sh --auto || status=1
+    fi
   elif [ -s /opt/src/ikev2.sh ]; then
 cat <<'EOF'
 ================================================

vpnsetup_amzn.sh

@@ -554,12 +554,20 @@ EOF
 set_up_ikev2() {
   status=0
   if [ -s /opt/src/ikev2.sh ] && [ ! -f /etc/ipsec.d/ikev2.conf ]; then
+    skip_ikev2=0
+    case $VPN_SKIP_IKEV2 in
+      [yY][eE][sS])
+        skip_ikev2=1
+        ;;
+    esac
+    if [ "$skip_ikev2" = "0" ]; then
       sleep 1
       VPN_DNS_NAME="$VPN_DNS_NAME" VPN_PUBLIC_IP="$public_ip" \
       VPN_CLIENT_NAME="$VPN_CLIENT_NAME" VPN_XAUTH_POOL="$VPN_XAUTH_POOL" \
       VPN_DNS_SRV1="$VPN_DNS_SRV1" VPN_DNS_SRV2="$VPN_DNS_SRV2" \
       VPN_PROTECT_CONFIG="$VPN_PROTECT_CONFIG" \
       /bin/bash /opt/src/ikev2.sh --auto || status=1
+    fi
   elif [ -s /opt/src/ikev2.sh ]; then
 cat <<'EOF'
 ================================================

vpnsetup_centos.sh

@@ -714,12 +714,20 @@ EOF
 set_up_ikev2() {
   status=0
   if [ -s /opt/src/ikev2.sh ] && [ ! -f /etc/ipsec.d/ikev2.conf ]; then
+    skip_ikev2=0
+    case $VPN_SKIP_IKEV2 in
+      [yY][eE][sS])
+        skip_ikev2=1
+        ;;
+    esac
+    if [ "$skip_ikev2" = "0" ]; then
       sleep 1
       VPN_DNS_NAME="$VPN_DNS_NAME" VPN_PUBLIC_IP="$public_ip" \
       VPN_CLIENT_NAME="$VPN_CLIENT_NAME" VPN_XAUTH_POOL="$VPN_XAUTH_POOL" \
       VPN_DNS_SRV1="$VPN_DNS_SRV1" VPN_DNS_SRV2="$VPN_DNS_SRV2" \
       VPN_PROTECT_CONFIG="$VPN_PROTECT_CONFIG" \
       /bin/bash /opt/src/ikev2.sh --auto || status=1
+    fi
   elif [ -s /opt/src/ikev2.sh ]; then
 cat <<'EOF'
 ================================================

vpnsetup_ubuntu.sh

@@ -664,12 +664,20 @@ EOF
 set_up_ikev2() {
   status=0
   if [ -s /opt/src/ikev2.sh ] && [ ! -f /etc/ipsec.d/ikev2.conf ]; then
+    skip_ikev2=0
+    case $VPN_SKIP_IKEV2 in
+      [yY][eE][sS])
+        skip_ikev2=1
+        ;;
+    esac
+    if [ "$skip_ikev2" = "0" ]; then
       sleep 1
       VPN_DNS_NAME="$VPN_DNS_NAME" VPN_PUBLIC_IP="$public_ip" \
       VPN_CLIENT_NAME="$VPN_CLIENT_NAME" VPN_XAUTH_POOL="$VPN_XAUTH_POOL" \
       VPN_DNS_SRV1="$VPN_DNS_SRV1" VPN_DNS_SRV2="$VPN_DNS_SRV2" \
       VPN_PROTECT_CONFIG="$VPN_PROTECT_CONFIG" \
       /bin/bash /opt/src/ikev2.sh --auto || status=1
+    fi
   elif [ -s /opt/src/ikev2.sh ]; then
 cat <<'EOF'
 ================================================