BrowserStack integration

Description

BrowserStack is a cloud web and mobile testing platform that enables developers to test their websites and mobile applications across on-demand browsers, operating systems and real mobile devices, without requiring users to install or maintain an internal lab of virtual machines, devices or emulators.

Proposal

Include BrowserStack integration into GitLab CI.

Links / references

SauceLabs integration at gitlab-ce#22755

Roadmap - CrossBrowser & Mobile Browser testing coverage and infrastructure

/cc @jlenny @NicoOchoa