when creating an isolated slave, set it to the master's initial binlog

this might defeat some weird usages of mysql_isolated_server but in
general it seems sane.

We provide some reaonsable defaults if given a server that didn't stash
away its position.
change default binlog position to 4
add reconnect!
have .down! not cleanup the process

it's useful occasionally to be able to down! a server and then 'up!' it
without clobbering the data
fix some requires
Merge pull request #4 from osheroff/isolated

Update isolated_server with the latest from mysql_isolated_server