Remove deprecated method.

View::addScript() has been replaced by view blocks.
Use assertContains() instead of more verbose approach.
Add support for themes + cells.

Cells should inherit the current View's theme and use it correctly when
rendering.
Clean up view bake templates output
Merge pull request #3403 from bcrowe/3.0-bake-templates

3.0 - Clean up view bake templates output
Add missing ConsoleIo method.

When updating the documentation, I noticed that styles() was missing on
ConsoleIo. This corrects that issue.
Merge pull request #3405 from cakephp/console-io-method

Add missing ConsoleIo method.
Add missing template file.
Rename action to template.

`template` better fits how the property is used in practice.
Merge pull request #3404 from cakephp/cell-theme

3.0 - Make view cells work with themes