PCBC-290: Use isset instead of directly checking the option.
Added toString method to Query classes.

You may now easily determine the exact query
that will be executed by calling the toString
method on any Query class.
Added missing getFromReplica operation.
Renamed `save` to `replace` as per the SDK 2.0 API.
Added common flags support.
PCBC-291: Undocument groupid, as it is experimental.