Add device emulation configuration

[Niall47]

• Enabling device emulation for Chrome and Edge via Selenium
• Adding common device emulation configs for ease of use
• Adding window_size arg (ignored if you also use emulation config)
• Break up the giant .method_missing method in meta_drivers.rb
• Added Rake tasks for every major browser configuration.
• Added playground/ directory with simple .html file server and proxy (intended to be used with the rake tasks for manual debugging)