Make sure assets is disable when --skip-sprockets is used
No need to give an example where there is generated code right there to serve as the example
deprecate `assert_blank` and `assert_present`.

They don't add any benefits over `assert object.blank?`
and `assert object.present?`
Merge pull request #8769 from senny/deprecate_assert_blank

deprecate `assert_blank` and `assert_present`.