#85 [registrar] add "force_q" parameter

[Iñaki Baz Castillo]

"registrar" module has "default_q" parameter that sets the "q" value in case there isn't in received REGISTER.

In my case I implement forwarding system (pararell and/or serial) by inserting entries in "location" table via web app, and playing with "q" value and LCR module (load_contacts() and next_contacts() functions).

But to set a parallel forwarding I need to know the "q" value of the "real" registered user (in fact I need to expect it's a known value).

For example: I use "default_q=500 (0.5)" so to set a parallel forwarding I insert via web an entry in "location" with q value = 0.5.
But maybe a SNOM or other phones could set a different "q" value during REGISTER and my system would fail if I expect "q" value to be 0.5.

Because of it, could be possible a new "force_q" parameter that forces the "q" value even if the user has registered a different one?