Enh livestatus query: finish with empty line.

Mostly for consistency purpose : 
always send every request to Livestatus with a supplementary \n so that the query ends by an empty line (\n\n) which is the main condition that livestatus use to detect the end of a query packet/string.

See https://github.com/pynag/pynag/pull/173 for reference.
Is this part of the code strictly necessary (same for the similar patch in __init__())

We have suffered in the past in pynag of doing to much 'prettifying' for caller functions and allow them to use badly formatted data and then have found ourselves in the situation of having to maintain backwards compatibility. We're not as bad as internet explorer 6, but almost :)

I think its better to remove this part, and if you feel strongly about having it in, file a separate bug and argue for its inclusion there.