remove volatile tests

Some tests relying on timings and external network resources were not
reliable and occasionally made builds on Travis fail.
Merge branch '2.3' into 2.4

* 2.3:
  [Validator] Backported constraint validator tests from 2.5
  Fix toolbar vertical alignment.
  [HttpFoundation] MongoDbSessionHandler supports auto expiry via configurable expiry_field
  [FrameworkBundle] add missing attribute to XSD
  Allow basic auth in url. Improve regex. Add tests.
  fix typos and syntax in Profiler controller method comments
  remove volatile tests
  [Console] fixed style creation when providing an unknown tag option
  [Validator] Convert objects to string in comparison validators. Reapplies 6cf5e0812e6f20d60acbc0324abf96475e89b6ef
  [HttpFoundation] Update QUERY_STRING when overrideGlobals

Conflicts:
	src/Symfony/Bridge/Doctrine/Tests/Validator/Constraints/UniqueValidatorTest.php
	src/Symfony/Component/HttpFoundation/Tests/RequestTest.php
	src/Symfony/Component/Validator/Constraints/AllValidator.php
	src/Symfony/Component/Validator/Constraints/CollectionValidator.php
	src/Symfony/Component/Validator/Tests/Constraints/AbstractComparisonValidatorTestCase.php
	src/Symfony/Component/Validator/Tests/Constraints/CallbackValidatorTest.php
	src/Symfony/Component/Validator/Tests/Constraints/EqualToValidatorTest.php
	src/Symfony/Component/Validator/Tests/Constraints/FileValidatorTest.php
	src/Symfony/Component/Validator/Tests/Constraints/GreaterThanValidatorTest.php
	src/Symfony/Component/Validator/Tests/Constraints/IdenticalToValidatorTest.php
	src/Symfony/Component/Validator/Tests/Constraints/ImageValidatorTest.php
	src/Symfony/Component/Validator/Tests/Constraints/LessThanOrEqualValidatorTest.php
	src/Symfony/Component/Validator/Tests/Constraints/LessThanValidatorTest.php
	src/Symfony/Component/Validator/Tests/Constraints/NotEqualToValidatorTest.php
	src/Symfony/Component/Validator/Tests/Constraints/NotIdenticalToValidatorTest.php
	src/Symfony/Component/Validator/Tests/Constraints/UrlValidatorTest.php