Fix test suite for ActiveRecord 3.x; assume primary key is INT if 'versions' table doesn't exist yet

gemfiles/3.0.gemfile

@@ -18,6 +18,9 @@ group :development, :test do
   gem 'rspec-rails', '~> 2.14'
   gem 'generator_spec'
 
+  # To do proper transactional testing with ActiveSupport::TestCase on MySQL
+  gem 'database_cleaner', '~> 1.2'
+
   platforms :ruby do 
     gem 'sqlite3', '~> 1.2'
     gem 'mysql2', '~> 0.3'

lib/paper_trail/version_concern.rb

@@ -70,6 +70,8 @@ module PaperTrail
 
       def primary_key_is_int?
         @primary_key_is_int ||= columns_hash[primary_key].type == :integer
+      rescue
+        true
       end
 
       # Returns whether the `object` column is using the `json` type supported by PostgreSQL