Update doctrine deps git locations

[codemonkee]

In [Part 3], DoctrineFixturesBundle

[DoctrineFixturesBundle]
    git=http://github.com/symfony/DoctrineFixturesBundle.git
    target=/bundles/Symfony/Bundle/DoctrineFixturesBundle

should be updated to

[DoctrineFixturesBundle]
    git=http://github.com/doctrine/DoctrineFixturesBundle.git
    target=/bundles/Symfony/Bundle/DoctrineFixturesBundle
    version=origin/2.0

In [Part 4], DoctrineMigrationsBundle

[DoctrineMigrationsBundle]
    git=http://github.com/symfony/DoctrineMigrationsBundle.git
    target=/bundles/Symfony/Bundle/DoctrineMigrationsBundle

updated to

[DoctrineMigrationsBundle]
    git=http://github.com/doctrine/DoctrineMigrationsBundle.git
    target=/bundles/Symfony/Bundle/DoctrineMigrationsBundle
    version=origin/2.0