Added AssociationObject and association for AllTypesObject. Also added
these to seeds.rb and added some objects with association preset.
Added last queries messages.
Extended read tests:
- Added find_each, find_batches, select, find_by_sql and count_by_sql
  execute methods.
- Added association finder options (eager_load, includes, joins,
  preload)
- Nicer displaying of finder options.
- Improved/fixed several other tests.
Improved/fixed several things in create, update and delete tests.