ice: fix IceTransport getLocalAddress/getRemoteAddress APIs

This patch contains following changes:

* getLocalAddress : wasn't return the negotiated IP if available
* getRemoteAddress : do not check for negotiation state
* some debug added

This fixes bugs during call establishement when IPv6 pair is negotiated,
but an IPv4 TURN is given as candidate (and not selected,
but used as default IP).

Change-Id: I89a973c16674b24cce35dc6dd9433554cb3a41bd
Tuleap: #891