easier to start mogilefsd in readonly mode

[GoogleCodeExporter]

If you lose you master databases for some reason, it is difficult to start 
everything in a read-only mode if you only have a slave remaining. To get this 
going, here's the steps we had to perform:

1) create a new mogilefs readonly user on the remaining slave, this user should 
have full access on tempfile and devices, but readonly on all other tables
2) update the devices table so that any alive devices are set to readonly (ex: 
update mogilefs.device set status='readonly' where status='alive';)
3) update your mogielfsd.conf to use the readonly user/database server
4) start mogilefsd

Original issue reported on code.google.com by [email protected] on 30 Sep 2012 at 10:26