removed deps checks in unit tests

As Composer is now widely used in the PHP world, having to run composer
install before running the test suite is expected. This also has the
nice benefit of removing a bunch of code, making things easier to
maintain (there is only one place to declare a dev dependency), and
probably more.
[HttpFoundation] added constants for HTTP status code in Response
fixed locale of sub-requests when explicitely set by the developer (refs #8821)
Fixed issue #6932 - Inconsistent locale handling in subrequests

The fix consists in passing the locale in the controller reference,
inside the routablefragment renderer.
added a functional test for locale handling in sub-requests
[HttpKernel] added a comment to warn about possible inconsistencies
[Form] Fixed: submit() reacts to dynamic modifications of the form children
Merge branch 'form-submit-2.2' into form-submit-2.3

Conflicts:
	src/Symfony/Component/Form/Form.php
	src/Symfony/Component/Form/Tests/AbstractFormTest.php
	src/Symfony/Component/Form/Tests/CompoundFormTest.php
	src/Symfony/Component/Form/Util/VirtualFormAwareIterator.php
[Form] Removed superfluous reset() call
[Form] PropertyPathMapper::mapDataToForms() *always* calls setData() on every child to ensure
that all *_DATA events were fired when the initialization phase is over (except for virtual forms)
Merge branch 'form-submit-2.2' into form-submit-2.3

Conflicts:
	src/Symfony/Component/Form/Extension/Core/DataMapper/PropertyPathMapper.php
[Form] Removed call to deprecated method
[Form] Removed exception in Button::setData(): setData() is now always called for all elements in the
form tree during the initialization of the tree
[Form] Added a test that ensures that setData() reacts to dynamic modifications of a form's children
fixed request format when forwarding a request
[Yaml] Fix comment containing a colon on a scalar line being parsed as a hash.
merged branch oscherler/yaml-comment-colon-fix (PR #8824)

This PR was squashed before being merged into the 2.2 branch (closes #8824).

Discussion
----------

[Yaml] Fix comment containing a colon on a scalar line being parsed as a hash.

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

Note: I only ran the Yaml Component tests.

This PR fixes a bug in YAML parsing where a comment containing a colon followed by a space, like this:

    foo # warning: this is a scalar with a comment, not a hash

was parsed as a hash, resulting in:

    array( 'foo # warning' => 'this is a scalar with a comment, not a hash' )

instead of:

    'foo'

Commits
-------

4563f1b [Yaml] Fix comment containing a colon on a scalar line being parsed as a hash.
[Form] Extracted ReferencingArrayIterator out of VirtualFormAwareIterator
Merge branch 'form-submit-2.2' into form-submit-2.3

Conflicts:
	src/Symfony/Component/Form/Util/VirtualFormAwareIterator.php
[Routing] fix phpdoc