Load ot without script-loader

The ot library is tricky to load with Webpack, as it writes
it's functions into a global `ot` object and does not export anything.
I got it working using `exports-loader` to put the `ot` object
into a CommonJS export and then forcing Webpack to only
load using CommonJS.

Signed-off-by: David Mehren <git@herrmehren.de>

package.json

@@ -133,7 +133,7 @@
       "url": "https://shivering-isles.com"
     },
     {
-      "name":"David Mehren",
+      "name": "David Mehren",
       "email": "hedgedoc@herrmehren.de"
     }
   ],
@@ -163,6 +163,7 @@
     "eslint-plugin-node": "11.1.0",
     "eslint-plugin-promise": "5.1.0",
     "eslint-plugin-standard": "4.1.0",
+    "exports-loader": "1.1.1",
     "expose-loader": "1.0.3",
     "file-loader": "6.2.0",
     "file-saver": "2.0.5",