Revert "Bump rack from 1.6.11 to 1.6.12 (#422)"
Revert "Bump rack from 1.6.11 to 1.6.12 (#422)"

This reverts commit 7ab5856d3c3c02cbe8749209c043a2fed7e2d2a7.

sass/sass-site,sass/sass-site,sass/sass-site