Set default configuration

[Norbert Orzechowicz]

At the momment after bundle registration we need to add something like this into app configuration:

fsi_data_source:
     twig: ~

We can avoid it chanigin following lines in file datasource-bundle/DependencyInjection Configuration.php

# line 28 - 31
                ->arrayNode('twig')
                    ->treatFalseLike(array('enabled' => false))
                    ->treatTrueLike(array('enabled' => true))
                    ->treatNullLike(array('enabled' => true))

into:

                ->arrayNode('twig')
                    ->addDefaultsIfNotSet()

After this simple modification twig will be used by default.