Debug::get_style() and Debug::_get_info_var() should be static

This fixes Deprecation Warnings like

```
[Mon Jul 01 12:04:49 2013] [error] [client 127.0.0.1] PHP Strict Standards:  Non-static method Baseapp\\Library\\Debug::_get_info_var() should not be called statically in /base-app/app/common/library/Debug.php on line 175
[Mon Jul 01 12:04:49 2013] [error] [client 127.0.0.1] PHP Strict Standards:  Non-static method Baseapp\\Library\\Debug::get_style() should not be called statically in /base-app/app/common/library/Debug.php on line 161
```