[HttpFoundation] getClientIp is fixed.

The getClientIp now returns ip of the earliest server in a proxy chain when all the servers in the chain are trusted proxies. Before this patch the getClientIp used to return null at such condition.
Some appropriate tests are added.
[Security] Removed unused var
[Intl] Refactored Locale component into two new components Icu and Intl
[Form] Changed component to use the Intl component
[Validator] Changed component to use the Intl component
[Locale] Added default locale
[Intl] Changed Intl::getStubIcuVersion() to Intl::getIcuStubVersion()
Fixed PHPDoc
[Form] Fixed failing tests
[Intl] Changed Intl::getIcuVersion() to return the stub version if the intl extension is not loaded
[Intl] Removed method IntlTestCase::skipIfInsufficientIcuVersion()
[Intl] Added autoload.php which was ignored by .gitignore
[Intl] Made the $locale parameter optional in the bundle interfaces
[Locale] Adapted to latest Intl changes
[Form] Adapted to latest Intl changes
[Validator] Adapted to latest Intl changes
[Intl] Updated the README file
[Intl] Fixed flawed PHPDoc
[Intl] Updated the README
[Intl] Moved the content of the README file to symfony/symfony-docs