add features to rake (and for Travis)

Rakefile

@@ -2,11 +2,17 @@ require "bundler/gem_tasks"
 
 require "rspec/core/rake_task"
 RSpec::Core::RakeTask.new(:spec)
-task default: :spec
+task default: [:spec, :features]
 
 require "guard/rake_task"
 Guard::RakeTask.new(:guard, "--plugin ronn")
 
+require "cucumber/rake/task"
+
+Cucumber::Rake::Task.new(:features) do |t|
+  t.cucumber_opts = "features --format pretty"
+end
+
 class Releaser
   def initialize(options = {})
     @project_name = options.delete(:project_name) do