ganeti-masterd: Some docstrings work
ganeti-masterd: Some docstrings work

- Add a docstring to IOServer's constructor
- Add argument description to PoolWorker's and JobRunner's ones

Reviewed-by: iustinp



yiannist/ganeti,andir/ganeti,grnet/snf-ganeti,apyrgio/snf-ganeti,dimara/ganeti,grnet/snf-ganeti,apyrgio/ganeti,bitemyapp/ganeti,apyrgio/snf-ganeti,yiannist/ganeti,andir/ganeti,leshchevds/ganeti,mbakke/ganeti,ganeti/ganeti,ganeti/ganeti,ganeti-github-testing/ganeti-test-1,bitemyapp/ganeti,mbakke/ganeti,onponomarev/ganeti,dimara/ganeti,mbakke/ganeti,leshchevds/ganeti,onponomarev/ganeti,yiannist/ganeti,apyrgio/ganeti,ganeti-github-testing/ganeti-test-1,andir/ganeti,leshchevds/ganeti,ganeti/ganeti