rename __tests__ to tests to fix #20

tests/preprocessor.js

@@ -0,0 +1,9 @@
+// preprocessor.js
+var ReactTools = require('react-tools');
+var to5 = require('6to5-jest').process;
+
+module.exports = {
+  process: function(src, filename) {
+    return ReactTools.transform(to5(src, filename));
+  }
+};