Adding quagga_interface type and provider

[m4ce]

Dmitriy, have a look at this.

I've also added support for the ipaddress parameter. I still need to add the logic around the ensure => shutdown. However, it handles the ensure => absent correctly now.

[m4ce]

I've actually added the enable option (true or false) to decide whether an interface should be enabled or shutdown. It seems to be cleanest really.

[bibigon812]

Can I remove the system interface?

[m4ce]

@bibigon812 - hm, I guess it will not actually remove the virtual device associated to the physical nic itself but it will effectively shut it down. However, let's say you define a new logical interface, e.g. tun0, and you want to remove it after, you still need a way of doing that, that is where ensure => absent comes in.

I guess 'ensure => absent' should be used with care. If one wants to enable or disable (shutdown) the interface, enable => true/false would do the trick.