Ignore Allow/DenyQOS in part if QOS not configured

Previous logic would fail an assert
Remove some v15.08 code

The perl API sbcast function included a step ID, which is NOT in v14.11, on v15.08
Perl API to return node MIXED state

Add new slurm_load_node flag of SHOW_MIXED, which will change a node's
state from ALLOCATED to MIXED by comparing the number of CPUs allocated
against the total CPU count on each node
bug 1209