Added a new services.yml file to comply with Symfony Best Practices
feature #727 Added a new services.yml file to comply with Symfony Best Practices (javiereguiluz)

This PR was squashed before being merged into the 2.6-dev branch (closes #727).

Discussion
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Added a new services.yml file to comply with Symfony Best Practices

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Commits
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55649c4 Added a new services.yml file to comply with Symfony Best Practices