cli option `--root` is broken

[mgreter]

Steps to reproduce:

git clone https://github.com/sass/sass-spec.git spec1
git clone https://github.com/sass/sass-spec.git spec2
ruby spec1/sass-spec.rb -r spec2/spec

Results in:

Test case ... is not within the spec directory spec1/spec

I suspect https://github.com/sass/sass-spec/blob/master/lib/sass_spec/test_case_metadata.rb#L42, since it does not seem to respect options[:spec_directory], but I failed to come up with something workable.

[nex3]

Closing this out since we've deprecated the Sass runner anyway.