Merge pull request #1 from nixsolutions/master

Updated travis.yml
Fix Declaration of Categories_Model_Category::addChild()
Fix "zf: command not found"
Fix "Declaration of Categories_Model_Category::addChild()" for php 5.3
Merge pull request #18 from naxel/master

Fix "Declaration of Categories_Model_Category::addChild()" and Fix "zf: command not found"