fix usage with composer loader where zend is not in include path

[nsams]

No description provided.

[fizzka]

hello. your fix works, great.

but it doesn't do it correctly: keep in mind, you must not to include vendor/autoload.php ;)

i think there are 2 ways:

1. add include path to composer.json (as in parent zendframework1)
   or
2. not to comment Zend_Loader::loadClass, but make fake call class_exists before