chore: bump engine.io-client and downgrade debug

The newer versions need to be transpiled to ES5, so we'll rollback for
now as it breaks IE11.

We'll have to find a way to provide the users who bundle the Engine.IO
(or Socket.IO) client (with webpack for example) with a source code
which does not include debug (or document the usage of
webpack-remove-debug [1]).

[1] https://github.com/johngodley/webpack-remove-debug

package.json

@@ -18,12 +18,12 @@
     "backo2": "1.0.2",
     "component-bind": "1.0.0",
     "component-emitter": "~1.3.0",
-    "debug": "~4.1.0",
+    "debug": "~3.1.0",
     "engine.io-client": "~3.4.0",
     "has-binary2": "~1.0.2",
     "indexof": "0.0.1",
-    "parseqs": "0.0.5",
-    "parseuri": "0.0.5",
+    "parseqs": "0.0.6",
+    "parseuri": "0.0.6",
     "socket.io-parser": "~3.3.0",
     "to-array": "0.1.4"
   },