added basic MySQL support for matching a token with an IP:PORT

The new command line option --sql-target-config     lets you specify  a file that looks like:

db=YOURDB
user=YOURUSER
passwd=YOURPASS
match_query=YOURQUERY

When someone connects to the proxy it will make a database connetion and run the query you specify to validate the users token.
the query should return 0 rows if the token is invalid, or return a row where the first column has the IP:Port