Let dump-auth-data take a profile limit

Now we have the option to pull only N of an application's pids. I switched us to
use optimist since we need more expressive power now.
Remove libmysqlclient

This is unused, but breaks some of our scripts on the pods because
`libmysqlclient` isn't installed.
Add script to migrate auth data

This moves the data straight from the profile store to the pod - no more writing
hundreds of MB of JSON to disk. It doesn't use `podClient` so we can run it from
production without having to deploy the `pods` branch prematurely.
Remove debug flag

Since auth data is merged, this would stick around forever. Don't want that.
Order pids during auth migration

This will let us batch them consistently if we want to, and lets us track where
we are during the run.