bug #846 Updating .lock files for security reasons (atamansv)

This PR was merged into the master branch.

Discussion
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Updating `.lock` files for security reasons

Currently, `composer install` as well as Travis CI fails, because of symfony/http-foundation (v4.1.1):

https://symfony.com/blog/cve-2018-14773-remove-support-for-legacy-and-risky-http-headers

![screen shot 2018-08-12 at 15 14 37](https://user-images.githubusercontent.com/1833361/44002460-14b8afc6-9e43-11e8-873e-d5182cd20849.png)

This PR updates the `composer.lock` and `symfony.lock` files to use the latest Symfony 4.1.3. Should also fix Travis breakage on #845.

Commits
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318d101 Updating `.lock` files for security reasons

Author: javiereguiluz

.travis.yml

@@ -13,7 +13,7 @@ env:
 matrix:
   fast_finish: true
   include:
-    - php: 7.1
+    - php: 7.1.18
     - php: 7.2
     - php: nightly
   allow_failures: