Don't require rails test/unit support

We use RSpec to test, no need to require it. Fixes

    invalid option: --pattern

output appearing at end of tests.

Author: tvdeyen

spec/spec_helper.rb

@@ -8,10 +8,9 @@
 end
 
 # Configure Rails Environment
-ENV["RAILS_ENV"] = "test"
+ENV["RAILS_ENV"] ||= "test"
 
 require File.expand_path("../dummy/config/environment.rb", __FILE__)
-require "rails/test_help"
 require "rspec/rails"
 require 'rspec/active_model/mocks'
 require "capybara/rails"