inconsistent handling of css case

[jdchmiel]

Unit test:
emogrifyLowercasesAttributeNamesFromStyleAttributes
verifies that inline css in uppercase is translated to lowercase.

Unit test:
emogrifyKeepsAttributeNamesFromCssInOriginalCasing
seems to verify that passed in css does not become lowercase.

I have separately verified that uppercase css in a <style> maintains its uppercase without translation. Is this by design or would you like a pull request to ensure all css is lowercase?

[oliverklee]

Hi, thanks for reporting this. Actually, both should be handled the same way. I'd say, we lowercase them all the time (be it from style attributes or the attached CSS) so we can handle cases where attributes get overwritten. (Of course, we need to cover this case with unit tests as well.)

A pull request would be awesome. ❤️

[jdchmiel]

Added this to #85 since they overlapped extensively.