bump slurm to v1.6.0: support backup controller and seff usage reporting
bump slurm to v1.6.0: support backup controller and seff usage reporting

https://github.com/CSC-IT-Center-for-Science/ansible-role-slurm/releases/tag/v1.6.0

 - https://github.com/CSC-IT-Center-for-Science/ansible-role-slurm/pull/76 remove unused variables and stop creating directory
 - Testing output in travis is now a bit easier to read.
   https://github.com/CSC-IT-Center-for-Science/ansible-role-slurm/commit/95941b7293444246dde7834522c46951dee82ebb
 - https://github.com/CSC-IT-Center-for-Science/ansible-role-slurm/pull/78  - allow running a slurm backup controller
 - https://github.com/CSC-IT-Center-for-Science/ansible-role-slurm/pull/79 send a slurm efficiency report if the user requests it
 - https://github.com/CSC-IT-Center-for-Science/ansible-role-slurm/commit/3cd2dbe50d957b92eac1ba8d482b981d8f37c691 Rename a few tasks so that all task names are unique

CSC-IT-Center-for-Science/fgci-ansible,mantti/fgci-tut,mantti/fgci-tut,mantti/fgci-tut