[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
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c195957 [Components] Tests/Autoloading fixes

Discussion
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Fix components

See #4141

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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.

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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.

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

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

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

Can you squash your commits before I merge? Thanks.

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

done

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

It does not seem that the commits are squashed.

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

done
[HttpFoundation] updated RFC references in Response
[HttpFoundation] added missing RFC reference
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
[HttpFoundation] fixed docblock typos in session class
[HttpFoundation][Session] change possible replace() & set() for set only()
[HttpFoundation][Session] Assume that memcache(d) instances are already configured
[Session] Pdo Handler cleanup
[Session] Fix the PDO handler for mysql concurrent write
[Session] Memcache/d cleanup, test improvements
merged branch vicb/session_pdo_storage (PR #4244)

Commits
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b865b09 [Session] Fix the PDO handler for mysql concurrent write

Discussion
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[RFC][Session] Make the PDO handler looks less hacky

Related discussion: https://github.com/symfony/symfony/commit/ebc2f01e5b4e567c49ae99cb6bd01b4d07039748#commitcomment-1304221

The current code works but looks hacky (`$dbTimeCol = CASE WHEN $dbTimeCol = :time THEN (VALUES($dbTimeCol) + 1) ELSE VALUES($dbTimeCol) END`).

Todo: wrap the mysql specific code in a `try...catch` if we choose this PR way (to be consistent with all other PDO invocations).

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by travisbot at 2012-05-10T07:50:39Z

This pull request [passes](http://travis-ci.org/symfony/symfony/builds/1293131) (merged b865b096 into 48099a85).
[Session] cleanup of the PDO storage