Upgrade PHPUnit to version 5

- Fix deprecated getMock
- Use PHPUnit 4 for PHP 5.5 build

Manually cherry-picked from PR
https://github.com/wallabag/wallabag/pull/2201

.travis.yml

@@ -55,6 +55,7 @@ branches:
 before_script:
     - if [[ $TRAVIS_PHP_VERSION != hhvm ]]; then echo "memory_limit=-1" >> ~/.phpenv/versions/$(phpenv version-name)/etc/conf.d/travis.ini; fi;
     - if [[ $TRAVIS_PHP_VERSION != hhvm ]]; then phpenv config-rm xdebug.ini; fi;
+    - if [ "$TRAVIS_PHP_VERSION" = "5.5" ]; then composer require "phpunit/phpunit:4.*" --no-update; fi;
     - composer self-update --no-progress
     - if [[ "$DB" = "pgsql" ]]; then psql -c 'create database wallabag_test;' -U postgres; fi;
 

composer.json

@@ -87,7 +87,7 @@
         "doctrine/doctrine-fixtures-bundle": "~2.2",
         "doctrine/data-fixtures": "~1.1.1",
         "sensio/generator-bundle": "^3.0",
-        "phpunit/phpunit": "~4.4",
+        "phpunit/phpunit": "~5.0",
         "symfony/phpunit-bridge": "^3.0",
         "friendsofphp/php-cs-fixer": "~1.9"
     },

tests/Wallabag/CoreBundle/EventListener/LocaleListenerTest.php

@@ -15,7 +15,11 @@ class LocaleListenerTest extends \PHPUnit_Framework_TestCase
 {
     private function getEvent(Request $request)
     {
-        return new GetResponseEvent($this->getMock('Symfony\Component\HttpKernel\HttpKernelInterface'), $request, HttpKernelInterface::MASTER_REQUEST);
+        $kernel = $this->getMockBuilder('Symfony\Component\HttpKernel\HttpKernelInterface')
+            ->disableOriginalConstructor()
+            ->getMock();
+
+        return new GetResponseEvent($kernel, $request, HttpKernelInterface::MASTER_REQUEST);
     }
 
     public function testWithoutSession()