[Process] In edge cases `getcwd()` can return `false`, then `proc_open()` should get `null` to use default value (the working dir of the current PHP process)
Removed underscores from test method names to be consistent with other components.

It is more common to use fully camel-cased names for test methods. Only some of the test methods are called with underscore notation. To avoid confusion it is better to be consistent.
Merge branch '2.0' into 2.1

* 2.0:
  Fix version_compare() calls for PHP 5.5.
  [Process] In edge cases `getcwd()` can return `false`, then `proc_open()` should get `null` to use default value (the working dir of the current PHP process)

Conflicts:
	src/Symfony/Component/Form/Extension/Core/ChoiceList/MonthChoiceList.php