Revert "DIGIPAL 398: added Source.priority field."

This reverts commit 4d69575a87d6927ee10e7c4a8975e6f954309eb3.
Revert "DIGIPAL 473: template does not exist. get_absolute_url() is set only for the models that have .has_absolute_url = True."

This reverts commit 024b85339aee3d004f2bf66b0e0beec471b7122b.
Revert "JIRA 462: Pagination of Manuscript Images inconsistent with other pages. Added count next to the title."

This reverts commit 849910e2c1d242c10d30ac0e4fda3b163485d7f9.
Revert "JIRA 462: Pagination of Manuscript Images inconsistent with other pages."

This reverts commit 623e8d30097e46e2404ba6efd1d730992fc2dcdf.