Allow for-each loop for ObjectNodes #33
Description
(note: PR exists -- FasterXML/jackson-databind#1590 -- but probably needs some changes)
So: 2.x API exposes Iterator approach, but that is bit clumsy. API should either be changed (which would be sub-optimal since this does not have to break), or augmented (probably preferable) to allow use of Iterable instead, both for field names and entries.