Correct queryEntities parameter index for initial call null value

The documentation states that the second parameter should be null for
the initial query to queryEntities.  The second parameter is the query
object, which should definitely not be null in the initial call.  The
third parameter is the continuation token, and this should be null in
the initial call.
Merge pull request #2292 from nattress/master

Correct queryEntities parameter index for initial call null value