Replace patches using sed and perl with pure php.

* Define PHPBREW_EXPECTED_PHP_DIR and PHPBREW_FIXTURES_PHP_DIR in
  phpunit.xml.
* Add a common interface of patch utility classes.
* Add a new class RegexpPatch which replaces a content of files using regexp.
* Add tests for Apxs2PatchTask, Patch64BitSupportTask, RegexpPatch,
  and RegexpPatchRule.
* Add an utility class which provides a way to create temprary files in
  tests.