Tidy up HTML Colour Names

With XHTML 1.0, the extended colour names are invalid, to make pfSense
as W3C compliant as possible, need to go back to using the HEX code.
Merge pull request #335 from ExolonDX/a0c0e8aefbac3e3979bac5fbfdecfedfe49cc2d3

Tidy up HTML Colour Names