Implement the new derivative structure.
Add the pid to the dsm.
Merge branch '7.x-derivatives' of github.com:jordandukart/islandora_solution_pack_pdf into 7.x-derivatives

Conflicts:
	includes/derivatives.inc
Display the error message in the failure output.
Merge pull request #55 from jordandukart/7.x-derivatives

Implement the new derivative structure.