New Perl module perl-Convert-Color (and its dependency perl-List-UtilsBy)

This adds the perl module Convert::Color, and also another dependency of its which is not already present in EL or repoforge: List::UtilsBy.

The specfiles are unmodified from cpanspec's default output, let me know if that does something you guys don't like - the resulting packages look fine to me, though.