Add compass-rails (master)

This appears to fix issues using asset paths helpers with the Living
Style Guide. See https://github.com/hagenburger/livingstyleguide/issues/70

Signed-off-by: Alex Coles <alex@alexbcoles.com>
Revert "Attempt workaround for LSG asset loading"

Adding compass-rails (previous commit 9689b158) solves the same issue.

This reverts commit 67e56122153a846a078118683c8e8195de1b5aa4.