Install PHPUnit via Composer and update to version 4.0.
Update composer before using it. Fixes openssl for https error.
Merge pull request #312 from bantu/phpunit-4-via-composer

Install PHPUnit via Composer and update to version 4.0.

* bantu/phpunit-4-via-composer:
  Update composer before using it. Fixes openssl for https error.
  Install PHPUnit via Composer and update to version 4.0.