minor #638 Updated Flex dependency (javiereguiluz)

This PR was squashed before being merged into the master branch (closes #638).

Discussion
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Updated Flex dependency

This is needed to fix #634 in a different way. Changelog:

```
  - Updating symfony/flex (v1.0.16 => v1.0.17)
  - Updating doctrine/common (v2.8.0 => v2.8.1)
```

Commits
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963fc33 Updated Flex dependency

Author: javiereguiluz

.travis.yml

@@ -18,7 +18,6 @@ install:
   - composer install
 
 script:
-  - cp .env.dist .env
   - ./vendor/bin/simple-phpunit
   # this checks that the source code follows the Symfony Code Syntax rules
   - ./vendor/bin/php-cs-fixer fix --diff --dry-run -v