Fix issues #41 and #42

This fix resets the cursor output buffer on each _putMessageId so that we don't get issues when a command raises an exception halfway through building message.   It also implements complete batch result reading instead of throwing at first error and provides a mechanism to get result update counts similar to JDBC.   This was whipped together pretty fast and isn't of immediate need, consider it a cursory review.   I just wanted to use python to fully test server side changes to executePreparedBatch implementation I can now do.   Would love to just hand it off if possible.
So this will just raise the last error encountered. Is that the typical behavior?