Change the results from cli.PollJob
Change the results from cli.PollJob

Curently PollJob accepts a generic job, but will return (history
artifact) only the first opcode result. This is wrong, as it doesn't
allow polling of a job with multiple results.

Its only caller (for now) is also changed, so no functional changes
should happen.

Reviewed-by: ultrotter, amishchenko

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