[ENHANCEMENT] create: Change "interface" to "ip4.addr = if|ip"

[tschettervictor]

Since I've started working on PR #783, I've noticed a few minor things that could be tweaked.

1. Classic jails get created in this following format

  interface = bastille0;
  ip4.addr = 10.0.0.1;

This makes it slightly difficult to deal with adding and removing interfaces from the jail.conf file.

I've currently implemented the following structure when creating jails
ip4.addr = bastille0|10.0.0.1

This makes it really easy to add multiple IP/interface pairs like the following example.

  ip4.addr = bastille0|10.0.0.1
  ip4.addr += bastille0|10.0.0.2
  ip4.addr += bastille0|10.0.0.3
  ip4.addr += bridge0|10.0.1.9

I will suggest editing create.sh (which I have done easily in my version) to just create classic jails in that way.

[bmac2]

I am ok with the change.

@yaazkal your thoughts?

[tschettervictor]

@JRGTH