Fix error closure overwriting in notStale

This caused a problem where the use of both wait and stale options
together could cause it to think that a lock was stale, when in fact
it was not stale.
Support lack of subsecond fs precision

Many filesystems lack subsecond precision in their stat
results, and Node didn't expose this until 0.11 anyway.

If the ctime is divisible by 1000, assume that we don't
have support for subsecond precision times, and round the
staleness option up to the nearest second.
v0.3.1