Demo App Broken [Missing Gem]

[0bserver07]

Bundler could not find compatible versions for gem "sass":
  In Gemfile:
    spree was resolved to 3.2.0.alpha, which depends on
      spree_frontend (= 3.2.0.alpha) was resolved to 3.2.0.alpha, which depends on
        bootstrap-sass (< 3.4, >= 3.3.5.1) was resolved to 3.3.5.1, which depends on
          sass (>= 3.3.0)

    sass-rails (~> 4.0.2) was resolved to 4.0.2, which depends on
      sass (~> 3.2.0)