Add support ppp in debian_ip.py

Hello! You lost support ppp in debian_ip.py. I added this. If i start "salt-call (v 2014.7)", i see error:
local: 
----------
          ID: network-dsl-provider
    Function: network.managed
        Name: dsl-provider
      Result: False
     Comment: 'dsl-provider'
     Started: 16:49:14.396052
    Duration: 2823.714 ms
     Changes:   

Summary
------------
Succeeded: 1
Failed:    1

I see all code and not can find error. You can help for me with this error?