minor #936 Change the visibility of WebTestCase::setUp to keep the same as in PHPUnit (lyrixx)

This PR was merged into the 2.0.x-dev branch.

Discussion
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Change the visibility of WebTestCase::setUp to keep the same as in PHPUnit

see https://github.com/sebastianbergmann/phpunit/blob/ea293f782b3e001c9b7eeb5bdc2d545e4c091fdb/src/Framework/TestCase.php#L1834

Commits
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7cddf2d0 Change the visibility of WebTestCase::setUp to keep the same as in PHPUnit

src/Silex/WebTestCase.php

@@ -29,7 +29,7 @@ abstract class WebTestCase extends \PHPUnit_Framework_TestCase
      * Note: Child classes that define a setUp method must call
      * parent::setUp().
      */
-    public function setUp()
+    protected function setUp()
     {
         $this->app = $this->createApplication();
     }