Simplify test setup

* Rely on bundler/setup to setup the load paths

test/paranoia_test.rb

+require 'bundler/setup'
 require 'active_record'
-ActiveRecord::Base.raise_in_transactional_callbacks = true if ActiveRecord::VERSION::STRING >= '4.2'
-
 require 'minitest/autorun'
-test_framework = defined?(MiniTest::Test) ? MiniTest::Test : MiniTest::Unit::TestCase
+require 'paranoia'
 
-require File.expand_path(File.dirname(__FILE__) + "/../lib/paranoia")
+test_framework = defined?(MiniTest::Test) ? MiniTest::Test : MiniTest::Unit::TestCase
+ActiveRecord::Base.raise_in_transactional_callbacks = true if ActiveRecord::VERSION::STRING >= '4.2'
 
 def connect!
   ActiveRecord::Base.establish_connection :adapter => 'sqlite3', database: ':memory:'