Refs #5800, add namespaces to integration tests in root folder. Also add IntegrationTestCase to a namespace, re-add individual test @groups, move test groups to class level, and rename test files & class names so underscores are not used.

Modified SetupFixture to save SQL dumps of fixtures when needed, make sure OmniFixture can be used w/ SetupFixture, and use SQL dump of OmniFixture in UI tests instead of running OmniFixture every time (so changes in fixtures do not result in changes to screenshots).

Allow UI testing system to specify extra plugins to load and install when running UI tests for a plugin.

When executing tests, check for non-core plugin that should be loaded by looking at test case class & current backtrace. (Removing need for enable_load_standalone_plugins_during_tests config option).

Piwik is a free/libre analytics platform. Refs #4455 GNU Package requirement to use free/libre instead of open source

(best practise is to test at least the minimum supported version)

Refs https://github.com/piwik/piwik/pull/300

Add new console command to setup fixture outside of a test so manual testing can be done w/ existing fixtures and so specific custom data can be added by creating a fixture. Includes slight refactor to Fixture.php.

Add config_override testing environment parameter that overrides INI config values, and make sure fixtures post testingenvironment hook so plugin test environment is enabled for fixtures.

- change idsite to idSite in Overlay URLs in piwik.js
- don't init top controls if top controls container can't be found
- add default parameter for $urls in SitesManager.setSiteAliasUrls so site alias URLs can be reset
- fix bugs in UI tests database setup (including moving dashboard setup to UITestFixture class & keeping outside of
  setUp function so --persist-fixture-data will work in case the super user is deleted)
- Add queryParamOverride testingEnvironment variable.
- fix screenshot testing page renderer's method of waiting for CSS images
- add margin bottom & left for widgetized controls for tests
- add diagnostics to upload_artifacts.sh script

- make updatetoken.php use TestingEnvironment in testmode,
- allow persisted fixture to be dropped using new --drop command line option (for ui test runner),
- fix debugging mistake in realtime map, fix merge error in empty.twig,
- make sure Fixture prints to screen only for UI test setup, re-enable CustomAlerts fixture in OmniFixture,
- make sure forced now value for realtime map is constant,
- use *.getDatabaseConfig events to override database name in TestingEnvironment
- use TestingEnvironment in proxy/piwik.php
- add wait() method to screenshot testing framework's PageRenderer
- hide current UTC time in manage websites admin screenshot