BibRank: small bug fix for citation indexing
BibSched: compatibility between --fixed-time and --limit

* When --fixed-time is set and a task is postponed we used the regular
  sleeptime (to respect the fixed time) instead of running as soon as possible
  (in this case the beginning of the allowed times by --limit)
  e.g. A task is scheduled to run between monday and friday and sleep 24 hours
       and is supposed to run at 7am.
       Old behavior, on saturday 7am, it is postponed to run on monday morning
       at midnight.
       New behavior, it is postponed to run sunday, 7am. On sunday it is
       postponed to monday 7am.
BibRecord: New record_get_field_values() func imported from Invenio

 * Updated version provides the ability to filter results.
Merge branch 'bibrecord-api-update' of ssh://lxplus.cern.ch/~/public/repo/invenio-inspire-ops-garmstro into bibrecord-api-update