Updating forwarding rule for service tunnel connectivity.

• Adding UDP forwarding rule which is essential for Service Tunnel connectivity from app on end user devices.
  Addressing #17

Optional EIP on instance for NAT use

Fixing issues #13 and #14

Persist iptables DNAT rules on reboot

Added iptables-persistent to instance so that we preserve the iptables DNAT rule after reboot.

Fix DSR issue in google cloud

It fixes a problem with service tunnels when using google cloud UDP load balancers

Solve open issues, fix bug with health checks on external NLBs

Merge pull request #9 from danhiris/main

v1.0.5

Update startup-script

Merge pull request #2 from danhiris/main

Solution for issue #1