ZF-267: Add video search to Zend_Service_Yahoo

Description

Zend_Service_Yahoo does not currently support Yahoo! video search.

Comments

Adds video search to Zend_Service_Yahoo.

Adds:

Zend/Service/Yahoo/VideoResult.php

Zend/Service/Yahoo/VideoResultSet.php

Modifies:

Zend/Service/Yahoo.php

Commited in r7340