Wrap the exception to get more information about where the exception comes from

Bug fix: no
Feature addition: yes
Backwards compatibility break: no
Symfony2 tests pass: yes
License of the code: MIT

This patch add more information about where the exception comes from.
Actual you get one exception
```
The service definition "fos_user.registration.form" does not exist.
```

After the patch you get
```
[2/2] Try to replace alias "fos_user.registration.form" with "hwi_oauth.registration.form". 
[1/2] The service definition "fos_user.registration.form" does not exist.
```