Update dependency socket.io to ~0.9.19 [SECURITY]

Author: renovate-bot

package.json

@@ -9,7 +9,7 @@
     "express": "3.1.0",
     "jade": "*",
     "less-middleware": "*",
-    "socket.io": "~0.9.13",
+    "socket.io": "~0.9.19",
     "coffee-script": "~1.6.1",
     "connect-coffee-script": "~0.1.1",
     "redis": "0.8.x",