Not compatible with Symfony 3.4

[tristanbes]

This lib seems not compliant with Symfony 3.4

Could not find class for service with id "behatch:context:debug"

Is what I get after enabling Behatch\Extension: ~ and adding behatch:context:debug context on my suite.

contexts: v2.7.1

[sanpii]

Thank you for testing.

I can’t reproduce the problem by including symfony/symfony 3.4@beta.

Can you provide more informations? Do you have other requirements?

[sanpii]

Following the PR #228, it’s probably better.