Added hasMethod() to Component and Object class

this allows implementing __call() in behaviors

See this forum topic for details:
http://www.yiiframework.com/forum/index.php/topic/46629-invoke-behavior-method-through-php-magic-method-call-dosent-work/
added unit tests and call to $behavior->hasMethod in Component
Merge pull request #836 from cebe/component-has-method

Added hasMethod() to Component and Object class