jstestnode

1. Now parses test results with lxml instead of the Selenium API, because Selenium API shows itself very slow for a high number of css selectors.
2. Added support for running tests with Selenium Remote and Appium. This enables us to use SauceLabs or Amazon's Services and also to host our own Appium cloud.

erp5testnode

1. Now every erp5testnode software release will automatically request a frontend instance for itself. This was required because none of the previously mentioned services offer IPv6 connectivity in the Selenium grid, so we needed an IPv4 address to access the backend of the test nodes.

@Tyagov, please review.