[BUGFIX]Prevent incorrectly capitalized CSS selectors from being stripped

Some wysiwyg editors seem to generate terrible CSS such as:
P {
    PADDING: 0PX;
    MARGIN: 0PX;
}
which due to the capitalized P was not being applied inline.
[BUGFIX] Apply CSS attribute names regardles of case, outputting lowercase attributes and selectors

p { MARGIN: 0PX; } was not being applied correctly from style block
all inlined css from passed in css and parsed out <style> blocks is now lowercase
Merge branch 'master' of github.com:jdchmiel/emogrifier