Try to fix nginx setup on travis. Includes new [tests] INI config parameter for port (since using port 80 is not allowed for normal users on linux).

Since autoloading is used now, do not manually include fixture files during tests. Fixes case when one plugin has issue in fixture class making it impossible to run tests (since the tests:run will just fail).

Workaround phpunit class loading issue caused by testing environment variables. Sometimes a test case class will be loaded before phpunit starts running (ie, in bootstrap.php), which causes the phpunit file loader to fail if a path to a test file is specified on the command line.

Allow multiple environments to be specified to Environment constructor. Add hook in EnvironmentManipulator to get extra environment names, and specify test environment this way instead of through detecting PIWIK_TEST_MODE.

Rename Piwik_TestingEnvironment to TestingEnvironment and move the class to Piwik\Tests\Framework namespace. Remove manual require statements.

Remove uses of Config::init(), Config::clear() and Config::setTestEnvironment(). Replace last w/ mock config class, which is closer to use of DI.

I also replaced the check that does a request against Piwik to check
whether it is installed with `SettingsPiwik::isInstalled()` as discussed
recently

On local it does not work and I have not figured out why.
Maybe it works on travis though?

This file is not in a class because it needs to be compatible with PHP 4.

refs #6635 if user has not configured test section but Piwik is installed then we can configure most parts for the user

refs #5940 moved files into a subfolder framework, added autoloader to remove duplicated code to load autoload.php and to be able to register more autoloaders (eg for test files) on demand. This I got read of many includes that had to be updated all the time and that had to be updated all the time when moving iles

refs #5940 we might stay backwards compatible this way for 2 months. moved some tests from unit to integration and explained when a test is a unit test, an integration test or a system test.

Get xhprof integration to work. Only setup xhprof once per php execution and correctly aggregate xhprof runs (xhprof aggregation will always normalize so we must aggregate ourselves).