feature #431 Show better message when SQLite is not enabled (uikolas)

This PR was squashed before being merged into the master branch (closes #431).

Discussion
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Show better message when SQLite is not enabled

As mentioned in #423
I added to show better error message in the browser, if SQLite is not enabled. (I think that message should contain about sqllite3 and pdo_sqlite to enable)
But i have have doubts, how to show it? As a exception or simple text response?

![error image](http://i.imgur.com/pHW8QQH.png)

Commits
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ee8099c Show better message when SQLite is not enabled

Author: javiereguiluz

app/config/services.yml

@@ -53,7 +53,8 @@ services:
     # the list of events listened by that class.
     # See http://symfony.com/doc/current/event_dispatcher.html#creating-an-event-subscriber
     app.console_subscriber:
-        class: AppBundle\EventListener\ConsoleEventSubscriber
+        class: AppBundle\EventListener\CheckSQLiteEventSubscriber
+        arguments: ['@doctrine.orm.entity_manager']
         tags:
             - { name: kernel.event_subscriber }