Make rake work again

rspec/core/rake_task includes rake. Requiring rake when already inside a
rake will cause all kinds of errors.

Rakefile

@@ -3,20 +3,9 @@ require 'bundler/setup'
 
 Bundler::GemHelper.install_tasks
 
-begin
-  require 'rspec'
-rescue Bundler::BundlerError => e
-  $stderr.puts e.message
-  $stderr.puts "Run `bundle install` to install missing gems"
-  exit e.status_code
-end
-
-require 'rspec/core/rake_task'
-
 desc "Run specs"
-RSpec::Core::RakeTask.new('spec') do |t|
-  t.pattern = 'spec/**/*_spec.rb'
-  t.rspec_opts = ["-c"]
+task :spec do
+  sh "bundle exec rspec -f progress"
 end
 
 desc "Default: Run specs"