Only adjust sys.path when required
Add support for running tests in Chrome via Selenium WebDriver

Also adds a more plugable way of adding new products and is rather easy to
extend to all other browsers that can use RemoteWebdriver
Factor out browser and executor support.

This is designed to make it easier to add support for new browsers and
means of running tests

--HG--
rename : testing/web-platform/harness/wptrunner/browser.py => testing/web-platform/harness/wptrunner/browsers/b2g.py
rename : testing/web-platform/harness/wptrunner/device_setup/app.zip => testing/web-platform/harness/wptrunner/browsers/b2g_setup/app.zip
rename : testing/web-platform/harness/wptrunner/device_setup/app_install.js => testing/web-platform/harness/wptrunner/browsers/b2g_setup/app_install.js
rename : testing/web-platform/harness/wptrunner/device_setup/app_management.js => testing/web-platform/harness/wptrunner/browsers/b2g_setup/app_management.js
rename : testing/web-platform/harness/wptrunner/device_setup/certtest_app.zip => testing/web-platform/harness/wptrunner/browsers/b2g_setup/certtest_app.zip
rename : testing/web-platform/harness/wptrunner/device_setup/device_setup.py => testing/web-platform/harness/wptrunner/browsers/b2g_setup/device_setup.py
rename : testing/web-platform/harness/wptrunner/device_setup/index.html => testing/web-platform/harness/wptrunner/browsers/b2g_setup/index.html
rename : testing/web-platform/harness/wptrunner/device_setup/manifest.webapp => testing/web-platform/harness/wptrunner/browsers/b2g_setup/manifest.webapp
rename : testing/web-platform/harness/wptrunner/device_setup/test.zip => testing/web-platform/harness/wptrunner/browsers/b2g_setup/test.zip
rename : testing/web-platform/harness/wptrunner/server-locations.txt => testing/web-platform/harness/wptrunner/browsers/server-locations.txt
rename : testing/web-platform/harness/wptrunner/executor.py => testing/web-platform/harness/wptrunner/executors/executormarionette.py
rename : testing/web-platform/harness/wptrunner/browsers/chrome.py => testing/web-platform/harness/wptrunner/executors/executorwebdriver.py
rename : testing/web-platform/harness/wptrunner/reftest-wait.js => testing/web-platform/harness/wptrunner/executors/reftest-wait.js
rename : testing/web-platform/harness/wptrunner/reftest.js => testing/web-platform/harness/wptrunner/executors/reftest.js
rename : testing/web-platform/harness/wptrunner/testharness.js => testing/web-platform/harness/wptrunner/executors/testharness_marionette.js
rename : testing/web-platform/harness/wptrunner/browsers/testharness_chrome.js => testing/web-platform/harness/wptrunner/executors/testharness_webdriver.js
rename : testing/web-platform/harness/wptrunner/gecko_runner.html => testing/web-platform/harness/wptrunner/testharness_runner.html
Reset runtestsb2g.py to remove bogus debug code