Speed up the test suite a bit

We can remove the call to bundle install since we are running rake
through bundler so all the dependencies are already installed.

Moreover, the call to `rake db:create` is necessary only if we are
testing against Rails 3.2 but this is not the case.

Running `time rake test`:

           user     system   total
  Before   178.47s  10.05s   3:47.44
  After    40.91s   4.15s    45.481

Author: robin850

test/support/sass_rails_test_case.rb

@@ -79,11 +79,6 @@ def within_rails_app(name, without_gems = [], gem_options = $gem_options)
         gem_options.each { |gem_name, options| modify_gem_entry gem_name, options }
         without_gems.each { |gem_name| remove_gem name }
 
-        FileUtils.rm("Gemfile.lock") if File.exist?("Gemfile.lock")
-
-        runcmd "bundle install --verbose"
-        runcmd "bundle exec rake db:create --trace"
-
         yield tmpdir
       end
     end