Merge branch 'queues-defaults' into 'master'

bob/pipelines/config/distributed/sge_default.py

bob/pipelines/config/distributed/sge_iobig_16cores.py

bob/pipelines/config/distributed/sge_iobig_16cores_1gpu.py

bob/pipelines/config/distributed/sge_iobig_48cores.py

bob/pipelines/config/distributed/sge_light.py

bob/pipelines/distributed/local.py

bob/pipelines/distributed/sge.py

bob/pipelines/distributed/sge_queues.py

doc/dask.rst

doc/py_api.rst

doc/python/pipeline_example_dask_sge.py

doc/python/pipeline_example_dask_sge_adaptive.py