Added proxied websocket support

Added websocket support through a proxied server

Author: jcoady

labextension/vpython/package.json

@@ -29,7 +29,7 @@
   "dependencies": {
     "@jupyterlab/application": "^1.1.3",
     "@jupyterlab/apputils": "^1.1.3",
-	  "@jupyterlab/coreutils": "^3.1.0",
+    "@jupyterlab/coreutils": "^3.1.0",
     "@jupyterlab/docregistry": "^1.1.3",
     "@jupyterlab/notebook": "^1.1.3",
     "@phosphor/disposable": "^1.3.0",