Allow functionality to skip a bench

[devinus]

  bench "String Escaping (JSEX)", [string: gen_string] do
    # JSX doesn't support escaping unicode, it's unsupported
    :timer.sleep(1000)
  end

Maybe color it red in the results?

[alco]

I don't understand. If there is nothing to benchmark, why write the test in the first place?

[devinus]

Well, I'm writing a suite of tests that test different functionality for different libraries, and sometimes a library simply wont have that feature.I'd like to not just exclude the test since it's slightly confusing unless you know it's unsupported.

[alco]

So you have the same benchmark suite for different libraries? If that is the case, that might not be supported for quite some time if at all. I'd like to keep benchfella narrow in scope for now.