Adds what will hopefully be treated as a comment by all npm versions to package.json.

package.json

@@ -23,6 +23,8 @@
       "sdp-simulcast": "0.1.0",
       "async": "0.9.0",
       "retry": "0.6.1",
+
+      "@comment": "Callstats.io does not work with recent versions of jsSHA (2.0.1 in particular)",
       "jssha": "1.5.0",
       "socket.io-client": "1.3.6"
   },