test: Renamed readme.md to README.md

.. and updated link in main README.md

(Github supports relative links now AFAIK)

README.md

@@ -67,7 +67,7 @@ Run the plovr web server (see above), and either open the `test/ol.html` file
 in the browser (e.g. <http://localhost:8000/test/ol.html>), or run `./build.py test`
 on the console (headless testing with PhantomJS, make sure to install it first from http://phantomjs.org/download.html).
 
-See also the test-specific [readme](https://github.com/openlayers/ol3/tree/master/test).
+See also the test-specific [README](test/README.md).
 
 ## Run the linter