[Components] Tests/Autoloading fixes

* Switched to Composer to manage "dev" dependencies
* Fixed READMEs
* Excluded vendor in phpunit.xml.dist files
* Fixed message in bootstrap.php files
* Added autoloader for the component itself
merged branch willdurand/fix-components (PR #4155)

Commits
-------

c195957 [Components] Tests/Autoloading fixes

Discussion
----------

Fix components

See #4141

----
This PR:

* configures each component to use composer to manage "dev" dependencies instead of env variables;
* adds phpunit configuration file on Filesystem component;
* fixes READMEs.

It's mergeable without any problems, but I would recommend to wait a fix in Composer in order to use `self.version` in `require`/`require-dev` sections.

Note: I kept `suggest` sections because it makes sense but this PR doesn't aim to provide useful explanations for each entry. It could be another PR, not that one.

---------------------------------------------------------------------------

by willdurand at 2012-04-30T20:43:13Z

@fabpot I reviewed each component, one by one. Now `phpunit` always works, even if tests are skipped. A simple `composer install --dev` allows to run the complete test suite. Each commit is well separated from the others. I guess, everything is ok now.

---------------------------------------------------------------------------

by Tobion at 2012-04-30T20:47:00Z

Please squash, as it makes no sense to have the same commit for each component.

---------------------------------------------------------------------------

by fabpot at 2012-05-01T14:26:11Z

Can you squash your commits before I merge? Thanks.

---------------------------------------------------------------------------

by willdurand at 2012-05-01T14:29:38Z

done

---------------------------------------------------------------------------

by fabpot at 2012-05-01T15:48:25Z

It does not seem that the commits are squashed.

---------------------------------------------------------------------------

by willdurand at 2012-05-01T15:54:08Z

done
updated minimum PHP version to 5.3.3

5.3.3 has some interesting fixes and this is the version used by
Redhat 6 and Debian 6
[2.1][Component][Yaml] fix 4022
merged branch gajdaw/2_1_component_yaml_fix_4022 (PR #4126)

Commits
-------

80a2a92 [2.1][Component][Yaml] fix 4022

Discussion
----------

[2.1][Component][Yaml] fix 4022

Bug fix: yes
Feature addition: no
Backwards compatibility break: no
Symfony2 tests pass: [![Build Status](https://secure.travis-ci.org/gajdaw/symfony.png?branch=2_1_component_yaml_fix_4022)](http://travis-ci.org/gajdaw/symfony)
Fixes the following tickets: #4121, #4022, #4135
Todo:

---------------------------------------------------------------------------

by stof at 2012-04-27T13:03:15Z

Why is it marked as ``[2.2]`` if it is a bugfix ?

@fabpot ping

---------------------------------------------------------------------------

by gajdaw at 2012-04-27T14:42:21Z

The title should be [2.1] - now it is correct.

I marked it 2.0 and PR was for 2.0 originally.

Fabien suggested that it should go to master branch: https://github.com/symfony/symfony/pull/4121#issuecomment-5362990

---------------------------------------------------------------------------

by fabpot at 2012-05-07T09:17:31Z

That does not work when you have something after the unindented collection:

    collection:
        key:
        - a
        - b
        - c
    foo: bar

---------------------------------------------------------------------------

by gajdaw at 2012-05-07T11:11:30Z

@fabpot Last commit contains test with your yaml:

    collection:
        key:
        - a
        - b
        - c
    foo: bar

Everything seems fine. Can you give me a hint: what do you mean, when you say "That does not work"?

---------------------------------------------------------------------------

by fabpot at 2012-05-07T12:36:19Z

Sorry, the failing test is the following:

    test: Key/value after unindented collection
    brief: >
        Key/value after unindented collection
    yaml: |
        collection:
            key:
            - a
            - b
            - c
            foo: bar
    php: |
        array('collection' => array('key' => array('a', 'b', 'c'), 'foo' => 'bar'))

---------------------------------------------------------------------------

by gajdaw at 2012-05-07T15:48:26Z

@fabpot Last commit passed your test.

---------------------------------------------------------------------------

by fabpot at 2012-05-07T17:28:21Z

Can you squash your commits? Thanks.

---------------------------------------------------------------------------

by travisbot at 2012-05-08T05:32:58Z

This pull request [fails](http://travis-ci.org/symfony/symfony/builds/1273487) (merged 20891c58 into 919604ab).

---------------------------------------------------------------------------

by gajdaw at 2012-05-08T05:36:51Z

Done.

---------------------------------------------------------------------------

by travisbot at 2012-05-08T07:23:47Z

This pull request [passes](http://travis-ci.org/symfony/symfony/builds/1274162) (merged 80a2a92e into 898ff4e0).
removed some files from check_cs as they have been fixed now
switched to use mbstring whenever possible instead of iconv