Make uploadFile have a callback

This should fix #80.

src/app.js

@@ -163,8 +163,9 @@ var run = function () {
     for (var i = 0; i < fileList.length; i++) {
       var name = fileList[i].name;
       if (!window.localStorage[utils.fileKey(name)] || confirm('The file ' + name + ' already exists! Would you like to overwrite it?')) {
-        editor.uploadFile(fileList[i]);
-        updateFiles();
+        editor.uploadFile(fileList[i], function () {
+          updateFiles();
+        });
       }
     }
 

src/app/editor.js

@@ -16,13 +16,14 @@ function Editor (loadingFromGist) {
     this.setCacheFileContent('');
   };
 
-  this.uploadFile = function (file) {
+  this.uploadFile = function (file, callback) {
     var fileReader = new FileReader();
 
     SOL_CACHE_FILE = utils.fileKey(file.name);
     fileReader.onload = function (e) {
       window.localStorage[SOL_CACHE_FILE] = e.target.result;
       sessions[SOL_CACHE_FILE] = null;
+      callback();
     };
     fileReader.readAsText(file);
   };