Remove compress option

[sindresorhus]

I just included it since it's an option in the original lib, but I feel it makes the task do more than one thing. gulp-csso would also do a much better job at compressing the CSS. I could rather recommend that task for compressing.

@contra @phated thoughts?

[yocontra]

I would remove it if something exists that does it better. The only time I think it's okay for a plugin to do multiple things like this is when they are logically coupled (like uglify not only minifying but compressing the JS).

[sindresorhus]

Agreed. Thanks :)