Support returning chunked query results within the same series

[jsternberg]

The InfluxDB server supports sending back a chunked response so that data can be sent back iteratively rather than all at once.

Unfortunately, the current implementation will only use chunked responses for these two reasons:

1. The name/tag of the series has changed.
2. It is returning the result of a different command.

So the following query will only return two chunks no matter how large the response.

SELECT value FROM cpu WHERE host = 'server01'
SELECT value FROM cpu WHERE host = 'server02'