Daint CI tests

Closes #202

see: https://user.cscs.ch/tools/continuous/

• register account in CSCS w/ invite to EM09 project from Raoul
• checkout SLURM batch system and SSH access (visibility from CI server)
• euler script re-factoring for portability (settings on top)
• @sukysjon fix cluster test example #204 (or use a different but working one)
• !174 (merged) - port current setup; cf. examples/randomwalk/submit-daint.sh