#2031 - Add class_exists() before method_exists() if class existence is unknown.
- fixed all instances of this in core code
- deleted previous Zend Guard Loader workaround in MY_Kohana.php
- updated Bootstrap.php to reflect deleted MY_Kohana.php
Merge pull request #176 from shadlaws/fix_2031

#2031 - Add class_exists() before method_exists() if class existence is unknown.