Bugfix/customer assigned name in uri (#65)

* dont force ice on srtp calls if not offered

* support customers creating their own dns name for our SBC IPs and putting that in the request-uri of INVITEs

data/srtp-transcoding.json

@@ -1,7 +1,7 @@
 {
   "default": {
     "transport-protocol": "UDP/TLS/RTP/SAVPF",
-    "ICE": "force",
+    "ICE": "default",
     "SDES": "off",
     "flags": ["generate mid", "SDES-no", "media handover", "port latching"],
     "rtcp-mux": ["require"]