change sync_delayed_jobs to be sync_delayed_jobs(delayed_job_classes) to perform only specified jobs
renamed the lineage ancestor and descendants

for now renamed to lineage_ancestor and lineage_descendant to avoid a clash with the hierachy structure. In the future it would be more
appropriate to change the hierachy to use parents/children since this is more suitable for the tree structure rather than a lineage.
Merge branch 'vln-merge' of https://github.com/SysMO-DB/seek into vln-merge
Merge remote-tracking branch 'lihua/vln-merge' into vln-merge
moved project_hierarchy_test_helper.rb out of integration tests

it is used by the unit tests too, and gave the confusing impression it only affected the integration tests