Stable TOR support, new providers and Docker builds

- Added fixtures support for the renderer endpoint

- Fixed FacebookCaptchaTo500 host detection
- Added support for using TOR with exit-point refresh

v1.3b

• Dropped support for PHP 7.0
• Wolnościowiec Prerenderer support
• Cache TTL parameter
• Parameter to disable external HTTP proxy via HTTP header (ww-no-external-proxy)

Introducing special endpoints

Special endpoints

ProxySelector
-------------
  Returns the IP address with port of a proxy which normally would be used to redirect the traffic
  Token is required to use the endpoint.
  
  Useful when need to render a page using eg. Chromium, so the browser could be spawn with proper arguments.
  See: https://github.com/Wolnosciowiec/frontend-prerenderer

GET /__webproxy/get-ip

1.1 New provider, Docker and Heroku configurations

Update README.md

Fixed a mistake in documentation

External proxies support is here, over 1000+ fresh IP addresses verified by extenal service every 10 minutes

• External proxy servers support
• Docker containers (currently for ARM/aarch64 only)