Add API for updating scenario settings to 'amoc_dist'
Add API for updating scenario settings to 'amoc_dist'

This functionality allows modifying scenario parameters
  while it is running.

- The whole 'amoc_dist' module is untested.
  This needs to be solved. It is not possible to test it easily
    as the whole cluster needs to be running.
  There is an integration test, but it has a significant overhead
    and does not generate coverage reports.
- Fixed some broken specs

esl/amoc