Thumbnail ingest

Cherry picked https://github.com/Islandora/islandora_solution_pack_audio/commit/7ae3c7a869e9859043b0c5842a475c8fce6dd63a
with conflicts.

Conflicts:
	includes/derivatives.inc
Add cherry-pick'd islandora_scale_thumbnail()

Cherry-picked from https://github.com/Islandora/islandora/commit/e8c566daa828fe679e45bece1c9d266439cf23b3

** THIS CODE SHOULD GET REPLACED when reposervice is moved to 7.x-1.3
or master.
Merge branch 'cherry-pick-tn-7ae3c7a869' into lyr-master

* cherry-pick-tn-7ae3c7a869:
  Add cherry-pick'd islandora_scale_thumbnail()
  Thumbnail ingest