Handle hyphenated CSS Properties

camelCase properties of style like borderCollapse need to be converted to hyphenated, like border-collapse

I haven't found a resource saying that this is universally true, but testing seems to confirm it and it looks correct based on http://www.w3.org/TR/DOM-Level-2-Style/css.html#CSS-extended

The specific issue I was looking to address is the style of the <table> element on the HTML export - it has a style attribute which contains "borderCollapse:collapse;" but it should be "border-collapse:collapse;"