Add LiipThemeBundle

Re-defined the config / user relation to be OneToOne bidirectionnal.
ConfigType is now a service so I can inject the list of available themes that are also used by LiipThemeBundle

Force sqlite for test
In case of people use a different driver in parameter.yml (yes I do :))

app/AppKernel.php

@@ -21,6 +21,7 @@ class AppKernel extends Kernel
             new JMS\SerializerBundle\JMSSerializerBundle(),
             new Nelmio\ApiDocBundle\NelmioApiDocBundle(),
             new Nelmio\CorsBundle\NelmioCorsBundle(),
+            new Liip\ThemeBundle\LiipThemeBundle(),
             new Wallabag\CoreBundle\WallabagCoreBundle()
         );