Karma integration

Following on from the previous PR, here we have:
* Karma integration, including:
* all conf in Gruntfile
* all jasmine removed
* specific jenkins parts (reporters, output files) removed
* rebased and PR'd to v3.1.0
* slightly cleaned up grunt multitask for karma files workaround

I think it all seems working, but TBH I've never run Karma except as a singleRun, so I can't be sure that what I'm seeing happen under 'watch' is correct. But it looks OK I think.