Fix dependency error on a non-existent argument when registration or resetting feature is disabled

[covex-nn]

If resetting feature is disabled, error The service "fos_user.mailer.default" has a dependency on a non-existent parameter "fos_user.resetting.email.from_email" is occured, when trying to send email.

A similar error occured when registration feature is disabled, but for fos_user.registration.confirmation.from_email parameter.

This PR fixes this bug

[covex-nn]

@XWB please review

[XWB]

Why would you disable the resetting feature in the recipe? What needs to be done is adding templating to framework.yml file.

[covex-nn]

There are 3 problems with recipe: templating, mailer and doctrine-bundle

templating cannot be added to framework.yaml automaticaly (see symfony/flex#247 (comment)), twig will be used instead of templating with special fos_user.mailer.twig_swift value;

and this configuration:

fos_user:
    registration:
        confirmation:
            enabled: false
    resetting: false

will remove requirement to mailer service. See FOSUserExtension.php and Compiler/CheckForMailerPass.php

[covex-nn]

Anyway this PR fixes a bug since #2639, it is not about recipe for Flex, but it could help with creating recipe, of course =)

[covex-nn]

I've temporary modified tests to show errors. See travis build

[covex-nn]

PR was rewritten, please review.

This PR fixes two bugs with non-existent parameter if registration or resetting feature is disabled. I've added tests, and PR is now ready again =)

[stof]

please don't create a new fos_user.from_email. Instead, set dummy values for these emails in case the other features are not used (they won't be used anyway in such case) or set the parameters directly.

[covex-nn]

@stof fixed. i've put dummy values to mailer.xml