Add options to set pap or chap or both on vlan.

easy to explain :

[pppoe]
verbose=0
ac-name=TEST
service-name=testservice
called-sid=mac
vlan-mon=eth1,2-2000-20024094
vlan-timeout=300
vlan-name=vlan%N
interface=re:^vlan(\d+)$
interface=vlan2001,pap

and options in cli to add or remove on the fly set witch vlan to use or to go in main (use both chap+pap)

if not set pap on vlan use main set :

[modules]
pppoe
auth_chap_md5
auth_pap
radius
ippool
shaper