FS-6462 --resolve

I found a problem here but it may not completely match your expectations.
I reviewed the RFC 4028 and checked against the code and I discovered we should not be putting a Min-SE in any response at all besides a 422:

section 5:

   The Min-SE header field MUST NOT be used in responses except for
   those with a 422 response code.  It indicates the minimum value of
   the session interval that the server is willing to accept.

I corrected this problem and implemented the 422 response so if you request a value lower than the minimum specified for the profile.
If the value is equal or higher to the minimum, it will be reflected in the Session-Expires header in the response and no Min-SE will be present.

libs/sofia-sip/libsofia-sip-ua/nua/nua_session.c

@@ -4502,9 +4502,9 @@ session_timer_add_headers(struct session_timer *t,
 
   sip_add_tl(msg, sip,
 			 TAG_IF(expires != 0, SIPTAG_SESSION_EXPIRES(x)),
-			 TAG_IF(min != 0
+			 TAG_IF((!uas || sip->sip_status->st_status == 422) && (min != 0
 					/* Min-SE: 0 is optional with initial INVITE */
-					|| !initial,
+					 || !initial),
 					SIPTAG_MIN_SE(min_se)),
 			 TAG_IF(autorequire && refresher == nua_remote_refresher && expires != 0, SIPTAG_REQUIRE_STR("timer")),
 			 TAG_END());