Routing: Introducing unittests for core app router classes

This PR introduces a large chunk of unittests to document the behavior of the core application routing classes.

This was made possible through the generous donation of the people mentioned in the following link via an Indiegogo campaign: http://joomlager.de/crowdfunding/5-contributors
Just to clarify: The behavior of createURI() was to either create JURI object from urls that were a "complete" relative URL, like 'index.php?option=com_content', but merge the current request variables into URLs that were similar to '&format=feed&type=rss' in order to complete them. A short time ago, the possibility of array-URL-parameters was introduced. With this change, those are behaving similar to the incomplete URLs now.