Restore gres functionality with select/linear

Logic introdiced in version 14.03.10 to support requeueing of jobs
with GRES allocated to currently running steps broke select/linear
due to differernces in the plugin logic. The commit with the bad
logic is 1209a664840a431428658c0950b16078af7aff63
Merge branch 'slurm-14.03' into slurm-14.11
Copy NEWS items from v14.03 up to v14.11.2