sauce_labs: fix typo in script path
sauce_labs: return the right status code

Just to_s returns a string on the form "pid <pid> status <status>",
while we need a number. If the process was killed, this can be nil, in
which case I'm using 127 as a code.
runner: add a wrapper for OS X connections

It turns out retries and some waits are good to have for reliability, so
putting this in a wrapper script seems sensible.