Require bundler/setup rather than calling Bundler.setup.

This allows bundler standalone to be used if the bundle dir
is added to the load path.

spec/spec_helper.rb

@@ -6,6 +6,8 @@
   SimpleCov.start do
     add_filter "/spec"
     add_filter "/features"
+    add_filter "/bin"
+    add_filter "/bundle"
 
     # internet_connection mostly contains logic copied from the ruby 1.8.7
     # stdlib for which I haven't written tests.
@@ -21,10 +23,7 @@
 end
 
 using_git = File.exist?(File.expand_path('../../.git/', __FILE__))
-if using_git
-  require 'bundler'
-  Bundler.setup
-end
+require 'bundler/setup' if using_git
 
 require 'rspec'