This commit patches PJSIP to not terminate with failure an ICE stream
transport during its initialization if a TURN is set
and this one is unreachable.

In such situation, as we don't try to negotiate with
remaining candidates, we don't let the session have a chance
to succeed with these candidates.

The commit also fixes an "over-trying" of contact
the TURN server: a contact phase is normaly done
PJ_STUN_MAX_TRANSMIT_COUNT (7 currently) time with
an incrementally sized duration between tries.
But the whole process is made PJ_TURN_MAX_DNS_SRV_CNT
time (was 4, changed for 1) even if it's always
the same IP. This leds with our current settings
to an very long time before contact phase timeout
(around 2 minutes!).

We also increase number of STUN servers per transport
(PJ_ICE_MAX_STUN) to 3 as we need 2 entries for
IPv4 and IPv6, and one set by user.

Finaly, our code is changed to not depend on an timeout
now for the Ring account ICE initialization
(the one for SIP), to let TURN registring enough time
to succeed. This fixes also blocking client issue
when it want to cancel the call during this init phase.

Change-Id: I1aa2e95c1668d4706213930526aaccaffbe0538d
Tuleap: #1047