pphtml should not treat "CSS used but not defined" as a "FAIL"

[windymilla]

It is not an error if a class name is used on an element, but that class is not used as a selector in the CSS.
It may be a mistake, e.g. a typo, so I think it is correct to "warn" about it, but it should not be a "FAIL"

I think the relevant line of code is this one where the word "FAIL" should be changed to "warn"

[asylumcs]

I agree. "FAIL" should more closely reflect what the CSS validator would flag. As long as it is still a "warn" it makes sense.

[cpeel]

This was resolved in #6