Zend Extension must use full path

Zend Extension must use full path, follow [this](http://xdebug.org/docs/install).

#### for example

    # it will install xdebug 2.2.4
    phpbrew ext install xdebug

#### /path/to/xdebug.ini

    #zend_extension=xdebug.so
    zend_extesion=/path/to/xdebug.so

And I also found problem of `$this->meta->getName` and `$this->meta->getPath` in `PhpBrew\Extension.php`. It retrun `xdebug` or `/path/to/xdebug`, but realpath is `xdebug-2.2.4`. So I make the extract path is `xdebug`, not `xdebug-2.2.4`.

Finally, I use new version of CLI Framework to rebuild phpbrew to solve Issue #214.