Fix formatting
Remove confusing sample code
Improve fixes
[Components][OptionsResolver] Fix&improve replaceDefaults() description
[Components][Console] Fix askConfirmation() description
add API link
Fix wrong list indentation
remove installation details for PHPUnit
Update installation.rst
Merge pull request #3251 from bicpi/mini_fixes

Mini fixes
Merge pull request #3264 from bicpi/improve_method_description

[Components][OptionsResolver] Fix&improve replaceDefaults() description
Merge pull request #3265 from bicpi/fix_method_description

[Components][Console] Fix askConfirmation() description
Merge branch '2.2' into 2.3
Updated required PHPUnit version

Running tests on version 3.6.4 ends with following error:

PHP Fatal error: Call to undefined method Symfony\Component\Form\Tests\SimpleFormTest::callback() in symfony/src/Symfony/Component/Form/Tests/SimpleFormTest.php on line 107
Merge branch 'issue-3162' of github.com:xabbuh/symfony-docs into xabbuh-issue-3162

Conflicts:
	contributing/code/tests.rst
fix code block indentation