See QA-19

• I haven't identified any code, tests, or docs for findRO(), find().readOnly(), etc - maybe I am not looking in the right places.
• I'm not seeing where V8STR_RO is getting set for cursor objects. I was able to set it up manually using:
  cur = db.c.find();
  cur._exec();
  cur._cursor['_ro'] = true;
  but maybe the helper still needs to be implemented or I didn't see it.
• I added some logging and I think I confirmed that once _ro was set, I could read a doc and write it using the original bson representation, as in the example for SERVER-3107.