change ALL_LEVEL to SYMFONY_LEVEL
minor #535 change ALL_LEVEL to SYMFONY_LEVEL (keradus)

This PR was squashed before being merged into the 1.0.x-dev branch (closes #535).

Discussion
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change ALL_LEVEL to SYMFONY_LEVEL

Resolve #464

Commits
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a05f4c9 change ALL_LEVEL to SYMFONY_LEVEL