Updates on Bats to Bats Core

[qaws01395]

I was encountering issues when running bats on my Git bash on Windows. When I read through some conversation online and figured out they have migrated to Bats Core.

It works well for me and the testing results looks exactly the same with Bats. Should we update the Readme and suggest to use Bats-core instead?

I'm new to open source but I wish to contribute to the community too. Not sure if it's appropriate posting this as a issue.

[bkhl]

It seems we started doing that in January but then forgot about it. Started #439 with that branch, with a few additional changes.