T6029: Rewritten Accel-PPP services to an identical feature set
Removed dhcp-interface option (l2tp)
Added wins-server (sstp)
Added description (ipoe, pppoe, sstp, pptp)
Added exteded-script (l2tp, sstp, pptp)
Added shaper (ipoe, pptp, sstp, l2tp)
Added limits (ipoe, pptp, sstp, l2tp)
Added snmp ( ipoe, pptp,sstp, l2tp)
Refactoring and reformated code.
(cherry picked from commit ac6a16f6c5ad7700789759e1ec093236c2e182a2)