Add closing and flushing of logging handlers
Add closing and flushing of logging handlers

In order for BitcoinTestFramework to correctly restart after shutdown, the
previous logging handlers need to be removed, or else logging will continue in
the previous temp directory. "Flush" ensures buffers are emptied, and "close"
ensures file handler close logging file.

peercoin/peercoin,DigitalPandacoin/pandacoin,DigitalPandacoin/pandacoin,DigitalPandacoin/pandacoin,peercoin/peercoin,peercoin/peercoin,DigitalPandacoin/pandacoin,DigitalPandacoin/pandacoin,DigitalPandacoin/pandacoin,peercoin/peercoin,peercoin/peercoin,peercoin/peercoin