Replace patches using sed and perl with pure php.

Hi, all.
I've implemented #343. This pull request is a bit large and might have architecutral design issues, so it would be helpful that you could point them out.

The summary of my changes is the following:

* Replace calls of sed and perl oneliners with `preg_replace` function calls.
* 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.
* Introduce PatchCollection class and it holds patch definitions now.
* Add tests for Apxs2PatchTask, Patch64BitSupportTask, RegexpPatch, PatchCollection, and RegexpPatchRule.
* Add an utility class which provides a way to create temprary files in tests.

Sincerely.