Improve the way PHPUnit is executed from Sonar

There are several way of executing phpunit. All of them explained in PHPUnit manual - see http://www.phpunit.de/manual/current/en/textui.html and http://www.phpunit.de/manual/current/en/organizing-tests.html

In short, at the moment the way you can execute PHPUnit within Sonar is:

• by using sonar.phpUnit.analyze.test.directory - if set to true (default value) it will pass test directory path to PHPUnit. If set to false it will use sonar.phpUnit.mainTestClass option
• by using sonar.phpUnit.mainTestClass - to point at suite file, commonly known as AllTests.php. That's the old way of executing PHPUnit, I believe it's not supported anymore. (will double check though)
• if file specified in sonar.phpUnit.mainTestClass doesn't exist and is set to false Sonar will execute PHPUnit using PHPUnit xml file.

Now:

• by default run PHPUnit using xml config file
• running tests from a given test folder is not default behaviour anymore
• don't add test dirs to phpunit cmd line when a custom phpunit xml file is provided
• sonar.phpUnit.mainTestClass - deprecated

Reasoning behind all of this - only using phpunit xml file we can create an accurate coverage report.