Update docs about boost on unix
Fix regression tests

Taught bitcoind to close the HTTP connection after it gets a 'stop' command,
to make it easier for the regression tests to cleanly stop.
Move bitcoinrpc files to correct location.
Tidied up the python-based regression tests.
Save/restore the memory pool at shutdown/startup

Save the memory pool in a 'mempool.dat' file at shutdown, and
read it in at startup.
Allow multiple regression tests to run at once

Choose ports at startup based on PID, so multiple regression tests
can run on the same system at the same time.
Have pull-tester run listtransactions/mempool_save tests