factory suggestions - use PimpleInterop

[dragoonis]

https://github.com/moufmouf/pimple-interop/blob/master/src/Interop/Container/Pimple/PimpleInterop.php

for factories
https://github.com/moufmouf/pimple-interop/blob/master/src/Interop/Container/Pimple/PimpleInterop.php#L120

each app package should return an array of factory classes, similar to factories.php in this PR.

See Zend\ModuleManager
See Zend "getServiceConfig()"

Example:

class PackageManager {
    public function registerPackageFactories(PackageCollection $packages) {
      foreach($packages as $package) {
          $packageFactories = $package->getFactories();
          foreach($packageFactories as $key => $val) {
               $container[$key] = $val;
          }
      }
    }
}

class PackageCollection {
  public function addPackage(PackageInterface $package);
}