Add option to return success or failure of the first child to exit

[paulerickson]

Scenario: Run Automated Tests and Dependencies Concurrently

Given I run a webserver and a test runner with --kill-others and --success first,
When the test runner completes
Then I expect concurrently to terminate the webserver
And return the exit code of the test runner, regardless of whether the webserver shut down gracefully

---

first will stop my test script from returning false positives and make me very happy, but I can't think of a case for last that isn't totally contrived... it just seemed like if I add first, then I should add last too.

[kimmobrunfeldt]

Thanks for the PR, I've thought about this functionality at some point too.

Could you format the code to be consistent with existing code? 4 space indentation etc. After that, this is ready to be merged.

[paulerickson]

Sure thing, @kimmobrunfeldt . I think it was just the indentation in main.js (blame vim), but correct me if I missed any other formatting points.

[kimmobrunfeldt]

Now merged and released, sorry that it took so long. https://github.com/kimmobrunfeldt/concurrently/releases/tag/1.0.0

[paulerickson]

Thanks!