Update socket.io

Our socket.io version is 2.0.4 while the current socket.io version is
2.1.1.

This patch updates socket.io to version 2.1.1 and takes care of the CDN
client version.

Signed-off-by: Sheogorath <sheogorath@shivering-isles.com>

package.json

@@ -115,8 +115,8 @@
     "sequelize": "^3.28.0",
     "sequelize-cli": "^2.5.1",
     "shortid": "2.2.8",
-    "socket.io": "~2.0.4",
-    "socket.io-client": "~2.0.4",
+    "socket.io": "~2.1.1",
+    "socket.io-client": "~2.1.1",
     "spin.js": "^2.3.2",
     "sqlite3": "^4.0.1",
     "store": "^2.0.12",