Uses sdp-simulcast 0.1.6 (fixes for RTX + simulcast).

package.json

     "pako": "*",
     "sdp-interop": "0.1.11",
     "sdp-transform": "1.5.*",
-    "sdp-simulcast": "0.1.5",
+    "sdp-simulcast": "0.1.6",
     "async": "0.9.0",
     "retry": "0.6.1",
     "jssha": "1.5.0",