Fix support for Android 6

Android 6 has a bug with IPSEC.

Bug information:

• Xiaomi MIUI forum
• Android bug 194269
• libreswan FAQ
• Information from parent repository (hwdsl2/docker-ipsec-vpn-server)

Ability to specify dns servers via vpn.env file

Ability to specify dns servers via vpn.env file

Fix operstates network state

Fix operstates network state

Using the docker Macvlan driver with a static IP, gives an "unknown" state. This patch allows it to work.
See https://www.kernel.org/doc/Documentation/networking/operstates.txt

Fix : Network Interface validation

Merge pull request #3 from Emirati/master

Fixed Network Interface validation

1.1.1

Fix : Forgot to rename VPN_IPSEC_INTERFACE to VPN_NETWORK_INTERFACE s…

1.1.0

Add custom network interface support.

THIS RELEASE IS BUGGY, DO NOT USE THIS ONE, USE 1.1.1 instead.