Adds 2i query operation.

Fixed bug in StoreOperation where secondary indexes were not
being stored.

Includes iTest for 2i query

Note that I went with the builder rather than fluent API here. This was because of the larger either/or set 
of conditions that needed to be checked. I *think* I'm going to end up going back and changing over all the 
ops to have a builder or static factory methods for consistency, but am open to discuss. 

Closes #317