Support node 8.x

[jan-molak]

Node 8 has recently become an LTS so it's time for Serenity/JS to support it properly.

Looks like the only dependency that we have that doesn't work on Node 8 is stacktrace-js

[Tom-Hudson]

@jan-molak - I should also point out that Protractor doesn't officially support node 8 yet. There is an ongoing issue with the debugger not working. It mean debugging using browser.pause() doesn't work. But everything else does.

However, I have tried running node 8 with Protractor without debugging working and it's like working blind sometimes!

[jan-molak]

Thanks for pointing that out @Tom-Hudson!

[ctaepper]

are there any plans/eta for this? we started to use serenity and we love it, however, our current project has requirements for node@^8.9.0