Composer handles ZF dependency and autoloading

Composer support has been added. Using 'composer update' downloads
the Zend Framework 1 dependency, from Packagist (can be changed in
the 'composer.json' file). There is no need to use git submodules.

Composer also handles autoloading the classes. Even though ZF1
uses 'require_once' statements, using Composer to do all autoload
is working.

Now, it is way easier to use OARA as a library in an existing PHP project, especially when it's managed by Composer (which is a standard nowadays).