fix (files) sendEncoded ignores async. This fixes #54

Author: illyaV

libs/backendless.js

@@ -3443,7 +3443,9 @@
                 return result;
             };
 
-        xhr.open("PUT", this.uploadPath, true);
+        var asyncHandler = this.asyncHandler;
+
+        xhr.open("PUT", this.uploadPath, !!asyncHandler);
         xhr.setRequestHeader('Content-Type', 'text/plain');
         xhr.setRequestHeader('application-id', Backendless.applicationId);
         xhr.setRequestHeader("secret-key", Backendless.secretKey);
@@ -3453,8 +3455,6 @@
             xhr.setRequestHeader("uiState", UIState);
         }
 
-        var asyncHandler = this.asyncHandler;
-
         if (asyncHandler) {
             xhr.onreadystatechange = function() {
                 if (xhr.readyState == 4) {