Add protoc-gen-php to bin list

[byrnedo]

If I add the repo as a dependency and then try and use protoc-gen-php it breaks saying it can't load autoload.php.

failed to open stream: No such file or directory in ..../vendor/skrz/meta/bin/protoc-gen-php on line 10
 require_once(): Failed opening required '....meta/bin/../vendor/autoload.php'

Could protoc-gen-php be added to the bin list in composer.json?

Edit: I realise now that won't even fix it. I found this stack chain which seems promising though:

http://stackoverflow.com/questions/30420629/php-autoloader-class-to-load-files-from-two-or-three-different-path