Make pupload work with #tree.
Changes based upon code review.
Merge branch '7.x-tree-fixes' of github.com:jordandukart/islandora_plupload into 7.x-tree-fixes

Conflicts:
	islandora_plupload.module
Merge pull request #8 from jordandukart/7.x-tree-fixes

Make pupload work with #tree.