Add CSS3 property names.

Taken from SCSS bundle: https://github.com/MarioRicalde/SCSS.tmbundle/blob/ed7b0310682603a856a646a2db2dbcf3787cedb0/Syntaxes/SCSS.tmLanguage#L1570

There is a comment in the SCSS bundle “Reversal order is important; KEEP IT” – so I kept it :-)

However, I removed the “…|[0-9]{1,3}\%|…” part from the regex, because I think it doesn't belong here (it matches percent values, not property names).
Make 'Documentation for Property' also work in source.scss scope.
Use system ruby for 'Documentation for Property'