Build: Uses different strategy to test bins status

Only 90% of the test should pass.

Related: https://github.com/sass/node-sass/issues/487#issuecomment-60902761 and https://github.com/sass/node-sass/issues/490.

/cc @andrew, @nschonni, @keithamus, @kevva
We should add [JSCS](https://github.com/jscs-dev/node-jscs) in our tests. :D

What do you propose here?