Swap lullabot/mink-selenium2-driver and lullabot/php-webdriver for justafish/mink-selenium2-driver and justafish/php-webdriver

Problem/Motivation

The dev dependencies lullabot/mink-selenium2-driver and lullabot/php-webdriver are no longer maintained by core maintainers.

Steps to reproduce

Proposed resolution

Swap to the forks at justafish/mink-selenium2-driver and justafish/php-webdriver which are maintained by @justafish, @alexpott and @longwave.

Remaining tasks

Make tagged releases.
Make the switch.
Backport to all active branches.

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet