Add FieldHandler for Name fields

[sensespidey]

Since it looks like #155 seems to be stalled, and I don't see another way of adding a project-level FieldHandler class to provide support for contributed modules, I need a way to support Name fields while creating entities with Drupal Driver.

I've implemented a simple NameHandler.php within the drupal-driver src namespace. It's extremely minimal for the moment, but serves my current purpose, so I won't bother to flesh it out further, since it probably shouldn't live here anyway. PR incoming.