BibSched: fixes for multi-node setup
BibSched: fixes for multi-node setup

* Kwalitee improvements in bibsched.py.

* Updates the check for the maximum number of running tasks
  in order to only count tasks running on the current node.
  (closes #925)

Reviewed-by: Samuele Kaplun <2e218f779e12714c314fad8ebf6b3041daa21337@cern.ch>

inveniosoftware/invenio,inveniosoftware/invenio,tiborsimko/invenio,tiborsimko/invenio