title: error on using rails_apps_composer w/ twitter-bootstrap less
body: <p>I'm trying to create a new app using rails_apps_composer.
  What went well some weeks ago doesn't work anymore.</p>
  
  <p>I'm using config vars:</p>
  
  <pre><code>:frontend: bootstrap
  :bootstrap: less
  </code></pre>
  
  <p>and for now composer breaks with several error messages as of</p>
  
  <pre><code>.rvm/gems/ruby-1.9.3-p194@testapp/gems/railties-3.2.8/lib/rails/railtie/configuration.rb:85:in `method_missing': undefined method `less' for #&lt;Rails::Application::Configuration:0x007fbb714356c8&gt; (NoMethodError)
  from .rvm/gems/ruby-1.9.3-p194@testapp/gems/twitter-bootstrap-rails-2.1.6/lib/twitter/bootstrap/rails/engine.rb:15:in `block in &lt;class:Engine&gt;'
  </code></pre>
  
  <p>When I use <em>sass</em>, it works. However, I have to use <em>less</em>.</p>
  
  <p>Gems are up to date:</p>
  
  <pre><code>twitter-bootstrap-rails (2.1.6)
  less (2.2.2)
  </code></pre>
  
  <p>I also tried to add <em>less</em> explicitly as an additional gem with the same result.</p>