removed several occurences of UserSettings plugin

CHANGELOG.md

core/API/Proxy.php

core/API/Request.php

core/Archive.php

core/Piwik.php

core/Plugin/ComponentFactory.php

core/Plugin/Manager.php

core/Url.php

core/ViewDataTable/Config.php

core/ViewDataTable/Factory.php

misc/others/api_internal_call.php

plugins/CoreHome/javascripts/dataTable.js

plugins/ScheduledReports/tests/Integration/ApiTest.php

plugins/TestRunner/TravisYml/TravisYmlView.php

plugins/Widgetize/Controller.php

tests/PHPUnit/Framework/TestCase/SystemTestCase.php

tests/PHPUnit/System/BlobReportLimitingTest.php

tests/PHPUnit/System/PivotByQueryParamTest.php