Move file type detection to protected method, making it reusable in child classes.
Skip test for PHP 5.2 as tested behavior is only applicable and testable for PHP 5.3+
Remove error suppresion in finfo_open so errors won't be hidden
Merge pull request #230 from OndraM/mime-tests-php52

Refactor mime type detection to be reusable; skip test in PHP 5.2
Merge branch 'hotfix/230'

Close #230