Optional dep dependencies improvment

[remicollet]

Discover in owncloud stack:

Owncloud pulls Monolog

• Monolog requires aws/sdk either v2 or v3
• aws/ask requires guzzle either v5 or v6
• owncloud requires guzzle v5 only

For now, the workaround is to load autoloader in correct order (Guzzle v5, Aws v2, Monolog)

BTW, we don't have any way in a package (e.g. Monolog) to NOT load aws sdk if already loaded.

I mean

\Fedora\Autoloader\Dependencies::madatory(array(
        '/usr/share/php/Aws/autoload.php',
));

Will load v2 autoloader

\Fedora\Autoloader\Dependencies::optional(array(
    array(
        '/usr/share/php/Aws3/autoload.php',
        '/usr/share/php/Aws/autoload.php',
)));

Will load v3, even if v2 already loaded by a previous call.

Improving this will require to manage a static list of already included files.