Updating tests around working with non-standard ActiveRecord models with non-sequence based primary keys.

* move into test/import_test so it runs across all supported adapters

[#60]

test/postgresql/import_test.rb

@@ -17,9 +17,4 @@ describe "#import" do
       assert_equal 1, result.num_inserts
     end
   end
-  
-  it "should import models whose primary key has no sequence if the primary key's value is specified" do
-    result = Widget.import Build(3, :widgets)
-    assert_equal 1, result.num_inserts
-  end
 end