deps: update socket.io to 2.x (#99)

This addresses a number of the snyk vulnerability warnings, remaining
will be fixed when socketio/socket.io-adapter#52
and socketio/socket.io-redis-emitter#61 are published.

Author: sam-github

package.json

@@ -8,7 +8,7 @@
     "debug": "^2.6.0",
     "express": "^4.14.1",
     "express-basic-auth": "^1.0.1",
-    "socket.io": "^1.7.2"
+    "socket.io": "^2.0.3"
   },
   "optionalDependencies": {
     "node-report": "^2.1.0"