fix: Replace fs with graceful-fs

[marcin992]

Karma sometimes exceeds the limit of open files in OS. Using of graceful-fs solves the problem.

Closes #544

[GitCop]

There were the following issues with your Pull Request

• Commit: 126a74c
  • Your commit message body contains a line that is longer than 80 characters
  • Commits must be in the following format: %{type}(%{scope}): %{description}

Guidelines are available at http://karma-runner.github.io/0.13/dev/git-commit-msg.html

---

This message was auto-generated by https://gitcop.com

[dignifiedquire]

Thanks a lot for this, this does make sense. Could you please make sure the testsuite is updated so the tests are passing please?

[marcin992]

Sure, I'll try to fix it soon.

[dignifiedquire]

@marcin992 ping

[testower]

I took the liberty to go over the tests and submitted another PR here: #1807

[dignifiedquire]

Fixed in #1807