The solution I used here is somewhat clever I think—all bootstrap files are now in their own /bootstrap subdirectory, which will prevent namespace conflicts and make customizations easier.
To import, we have a boostrap.scss and bootstrap-responsive.scss -- bootstrap-responsive.scss is no longer deprecated! No changes need to be made to import definitions from the previous version, and the name would even avoid namespace conflicts with files called 'responsive.css' in the root. In addition, upgrading will be a straight copy of the css/ directory from sass-twitter-bootstrap into our vendor/assets/stylesheets/bootstrap dir. Perfect on all fronts.
