Don't use `require('./run-log.js').runLog`

If you happen to introduce a circular require into the stack, this
object will be undefined.

Instead, hang on to `require('./run-log.js')`, which is the exports
module which does get filled in later.
upgrade mongo to 1.4.0-rc9 from a fork of 1.3.19
checkpoint towards running multiple mongods

still need to make onExit blow it all up