Update docs/languages/en/user-guide/unit-testing.rst

There is no test about what is returned.
Update docs/languages/en/modules/zend.http.client.advanced.rst

Fixed a code snippit on setting custom headers.
Update AdapterOptions Namespace Default

Updates the `Zend\Cache\Storage\Adapter\AdapterOptions` default `namespace` option to what is defined in the file.
Update docs/languages/en/modules/zend.console.adapter.rst

When using this example I found that the "use .. as Console" was referencing Zend\Console\AdapterInterface instead of Zend\Console\Adapter\AdapterInterface

This caused an error when passing the function a Windows console.

PHP Catchable fatal error:  Argument 1 passed to Album\Controller\SetupController::getConsoleUsage() must be an instance of Zend\Console\AdapterInterface, instance of Zend\Console\Adapter\Windows given, called in...
Merge pull request #582 from chrishiebert/patch-1

Update docs/languages/en/modules/zend.console.adapter.rst
Merge pull request #581 from jbottigliero/master

Incorrect Cache Adapter Default Namespace
Merge pull request #580 from AIResearcher/patch-1

Update docs/languages/en/modules/zend.http.client.advanced.rst
Minor change
Clarification of global.php placement

Clarification of global.php placement in docs/languages/en/user-guide/database-and-models.rst
Merge pull request #573 from exoon/patch-3

Update docs/languages/en/user-guide/unit-testing.rst