Changed test library to mocha and refactored the implementation

[frerom]

When the testla library was added as a dependency there was a circular dependency issue. Testla uses get-parameter-names. I changed the testing library to mocha and wrote new tests and also refactored the code so it is hopefully easier to follow. The only new behaviour of this snippet is that get-parameter-names throws an exception if a function isn't provided.

[goatslacker]

Makes sense to move away from testla. I dislike Mocha but I'm not opposed to switching to it.

Your implementation won't work for:

function flip(
  a,
  b
) {
  return b;
}

Also, can you please port over the current tests to mocha as well?

[frerom]

All valid points. I will fix this today!

[frerom]

I ported the tests to mocha and merge with your knew implementation. Also added a couple of semi-colons to the new implementation.

[goatslacker]

Thanks for the pull request

[frerom]

no problem!