Be compatible with PHPUnit installed with composer.

Doing a class_exists() check is a simple way to check for PHPUnit being
installed via an autoloader. It also keeps things compatible with
a Vendor dir installation.

Fixes #3721
Remove test case that is no longer useful.

It is impossible for the current test to ever fail in the test suite, as
PHPUnit will always be loaded.
correct coding standards
Fix docblock of bake template
Ensure referrer is saved in session even when AuthComponent::$loginRedirect is set.
Clarified redirectUrl() docblock.
Avoid unnecessary calls to ConnectionManager::enumConnectionObjects() in ClassRegistry::init().
Closes #3724
Merge pull request #1200 from ADmad/2.3-classregistry

Avoid unnecessary calls to ConnectionManager::enumConnectionObjects() in...
Add missing App::uses() to avoid fatal error
Merge pull request #1201 from cakephp/master-app-uses

Add missing App::uses() to avoid fatal error
Fix docblock typo of ObjectCollection class
Merge pull request #1204 from bcrowe/master

Fix docblock typo of ObjectCollection class
spelling correction.
Fixing tag generation for Html::script() and Html::css() when using 'fullBase' => true.

Changing values on array_diff_key() from empty ('') to null as they have no consequences and offer better readability.
Backwards compat for auth in the config array of HttpSocket::request()
Brings functionality back in line with docs as well
Merge pull request #1207 from renansaddam/supportFullBaseOnScriptAndCss

Fix missing support for fullBase in script() & css()

HtmlHelper::script(), HtmlHelper::css() did not have support for fullBase
added when it was added to image(). Fix that omission.
Merge pull request #1203 from cincodenada/patch_httpsocket

Add a bit of backwards compatibility for specifying auth in the config.

Restore compatibility with older versions when providing auth data in the
request data.
Try to fix random test failures on postgres.

Sorting in postgres is undefined and no based on the primary key when
sorting is not supplied.
Fallback to the default renderer if the config key is missing.
Fix CS error
Make JS,CSS,IMAGES conditionally defined.

This allows app's to redefine these constants as necessary.
This makes these constants consistent with their *_URL relatives.
Fixes #GH-1170