fix(DEV-8775): Makes UMD importable in Node

Set the webpack output globalObject to something more generic, so that
React no longer depends on "window"

Fixes #129 #107

Author: nathanbuchar

webpack.config.js

@@ -16,6 +16,7 @@ const config = {
     library: 'HelloSign',
     libraryExport: 'default',
     libraryTarget: 'umd',
+    globalObject: 'typeof self !== \'undefined\' ? self : this',
   },
   module: {
     rules: [