Allow running instances to be put online
Allow running instances to be put online

If an instance is running (eg. ERROR_up) and at the same time offline,
there's no way to either shut it down or reonline it. This allows
onlining it. Offlining is still disabled for running instances.

Signed-off-by: Guido Trotter <f62ca4d5358bdaeef0e50e57f9f7e231de63727e@google.com>
Reviewed-by: Iustin Pop <acf83a5274f31a43af6b914614365999469c1a31@google.com>

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