Change ColorKeyword to use source_from_range again
Change ColorKeyword to use source_from_range again

This was changed in f3a8839, but actually changes the behavior as the
Sass parser can potentially normalize the values here. We want to ensure
we are _always_ reading from the original source.

Change-Id: Ibeeb7525ff943018821312e2708db978d465e384
Reviewed-on: http://gerrit.causes.com/37974
Tested-by: jenkins <d95b56ce41a2e1ac4cecdd398defd7414407cc08@causes.com>
Reviewed-by: Shane da Silva <6f6e68d1df92f30cb4b3ce35260ddf94a402f33d@causes.com>

gajus/scss-lint,bkeepers/scss-lint,ingdir/scss-lint,chatzipan/scss-lint,golmansax/scss-lint,leseulsteve/scss-lint,teoljungberg/scss-lint,davecarter/scss-lint,baileyparker/scss-lint,cih/scss-lint,gatero/scss-lint,dwayhs/scss-lint,philipgiuliani/scss-lint,ivantsepp/scss-lint