test: use lowercased filenames in test runner

test/test.js

@@ -1,4 +1,4 @@
 require('fs').readdirSync(__dirname).forEach(function(f) {
-  if (f.substr(0, 5) === 'test-')
+  if (f.substr(0, 5).toLowerCase() === 'test-')
     require('./' + f);
 });