Convert ActiveModel to 1.9 hash syntax.

I also attempted to fix other styleguide violations such as
{ a: :b } over {a: :b} and foo(b: 'bar') over foo( b: 'bar' ).
Merge pull request #10408 from patricksrobertson/convert_activemodel_to_new_hash_syntax

Convert ActiveModel to 1.9 hash syntax.
Extract tests code out from AR's base_test.rb to integration_test.rb

`AR::Base#to_param` and `AR::Base#cache_key` is defined at
active_record/integration.rb, so tests for those methods should be at
integration_test.rb
Merge pull request #10396 from tkhr/extract-test-code-from-base_test.rb

Extract tests code out from AR's base_test.rb to integration_test.rb
Fix failures in AS with minitest 4.7.4
Remove not used module from initializable test
Fix typo in test
Fixes Dependency bug in Active Support

DateTime defined in date.rb
Merge pull request #10414 from eiel/fix_dependency

Fixes Dependency bug in Active Support
Merge pull request #10412 from vipulnsward/fix_callback_test_typo

Fix typo in test
Add test for `AR::Base#to_param`

According to the doc of `AR::Base#to_param`(
https://github.com/rails/rails/blob/04cda1848cb847c2bdad0bfc12160dc8d554
7775/activerecord/lib/active_record/integration.rb#L18 ), it returns
`nil` if the record is not persisted.
Merge pull request #10416 from tkhr/add-test-for-AR--Base#to_param

Add test for `AR::Base#to_param`