ensure Mapping is loaded for each db-driver

FOSUserBundle is informed to load the other db-drivers when needed
fix missing 'use_listener' for user-systems and db-driver

Each enabled db-driver has exactly one user-listener
which is only performed when 'use_listener' is enabled
for the user-system

Note. A listener can be registered multiple times (overwritten)
its not possible to do this in a CompilerPass as they run to late
improve functional testing

Don't remove the container for the same configuration
and drop the testing database after every test

Removing the container failed randomly so this is the best approach
(and also provides us with a big speed boost)
fix CS and composer.json duplicate package
Merge pull request #37 from rollerworks/feat-multi-storage

This PR was merged into rollerworks:master branch.

Discussion
----------

Support for multiple db-drivers

                           
|Q            |A          |
|---          |---        |
|Bug Fix?     |y          |
|New Feature? |y          |
|BC Breaks?   |n          |
|Deprecations?|n          |
|Tests Pass?  |y          |
|Fixed Tickets|GH-31 GH-33|
|License      |MIT        |
                           

This adds support for using multiple db-drivers (one per user-system), and fixes some related bugs.

Commits
-------

6e40632a3f031f8d7f247dbae514dd05cd70cd00 ensure Mapping is loaded for each db-driver

FOSUserBundle is informed to load the other db-drivers when needed sstok
086a41a7de8d793a4fb6dcf008761999d5362416 fix missing 'use_listener' for user-systems and db-driver

Each enabled db-driver has exactly one user-listener
which is only performed when 'use_listener' is enabled
for the user-system

Note. A listener can be registered multiple times (overwritten)
its not possible to do this in a CompilerPass as they run to late sstok
5dce4f962091394a9891518ae8a66fefc06e0a38 improve functional testing

Don't remove the container for the same configuration
and drop the testing database after every test

Removing the container failed randomly so this is the best approach
(and also provides us with a big speed boost) sstok
b13c1ccb737a1d986c4d12778b4bc2ed1a911d29 fix CS and composer.json duplicate package sstok