legacy: tasklets configuration and loading
legacy: tasklets configuration and loading

* Adds configuration variable CFG_BIBSCHED_TASKLET_PACKAGES, which
  defines which packages to load tasklets from.

Signed-off-by: Lars Holm Nielsen <7eaffca9f7cd98839b5821d0d23e09ff764b82cd@cern.ch>

tiborsimko/invenio-base,tiborsimko/invenio-base,inveniosoftware/invenio-base,inveniosoftware/invenio-base