do not pollute the global object

javascript/olm_prefix.js

@@ -1,3 +1,4 @@
+var Olm = (function() {
 var olm_exports = {};
 var onInitSuccess;
 var onInitFail;

javascript/olm_suffix.js

@@ -17,16 +17,20 @@ olm_exports['init'] = function(opts) {
     return olmInitPromise;
 };
 
+return olm_exports;
+
+})();
+
 if (typeof(window) !== 'undefined') {
     // We've been imported directly into a browser. Define the global 'Olm' object.
     // (we do this even if module.exports was defined, because it's useful to have
     // Olm in the global scope for browserified and webpacked apps.)
-    window["Olm"] = olm_exports;
+    window["Olm"] = Olm;
 }
 
 if (typeof module === 'object') {
     // Emscripten sets the module exports to be its module
     // with wrapped c functions. Clobber it with our higher
     // level wrapper class.
-    module.exports = olm_exports;
+    module.exports = Olm;
 }