PHP 5.2 fixes

[dannyvankooten]

Prevents fatal errors when running from PHP 5.2.

• Autoloader should be included by its absolute path, to prevent clashes with include_path setting.
• Put namespace into a string to prevent parse errors.
• Use a PHP 5.2 compatible autoloader since WPUpdatePHP is used for version checking.

[remkus]

See #3

[dannyvankooten]

Thank you @defries. Saw it!

[remkus]

Happy to help :)

[barrykooij]

thanks buddy