Add a custom str() method for objects.Disk
Add a custom str() method for objects.Disk

This is done in order to easy debugging of disk-related issues.

Reviewed-by: imsnah


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