Advanced optimisations should be disabled for CleanCss component

[ilikesleeping]

Some the optimisations in CleanCss can break stylesheets for IE8, for example the merging of background-size properties into the main background declaration. This sucks, as generating IE8 stylesheets is what I assume this component is mainly used for!

CleanCss also has a "compatibility" mode, which would disable optimisations that would break old IEs, so it might be helpful to use that by default, rather than having to disable CleanCss completely, as it is otherwise quite useful.

[daverodriguez]

It looks like this has been changed to allow passing an object with cleanCss options. Can you please update NPM with the newest version? 0.0.6 is missing this feature. Thanks!