Update Symfony and Doctrine to RC2

RC2 is out for both Symfony and Doctrine Common. This patch updates them via Composer.

Updating dependencies
- Removing symfony/class-loader (v2.1.0-RC1)
- Installing symfony/class-loader (v2.1.0-RC2)
Downloading: 100%

- Removing symfony/dependency-injection (v2.1.0-RC1)
- Installing symfony/dependency-injection (v2.1.0-RC2)
Downloading: 100%

- Removing doctrine/common (2.3.0-RC1)
- Installing doctrine/common (2.3.0-RC2)
Downloading: 100%

- Removing symfony/http-foundation (v2.1.0-RC1)
- Installing symfony/http-foundation (v2.1.0-RC2)
Downloading: 100%

- Removing symfony/event-dispatcher (v2.1.0-RC1)
- Installing symfony/event-dispatcher (v2.1.0-RC2)
Downloading: 100%

- Removing symfony/http-kernel (v2.1.0-RC1)
- Installing symfony/http-kernel (v2.1.0-RC2)
Downloading: 100%

- Removing symfony/routing (v2.1.0-RC1)
- Installing symfony/routing (v2.1.0-RC2)
Downloading: 100%

- Removing symfony/yaml (v2.1.0-RC1)
- Installing symfony/yaml (v2.1.0-RC2)
Downloading: 100%

Writing lock file
Generating autoload files