Backport - (jrao) LRDOCS-519 Added tool for removing unused images from a document's images directory
LRDOCS-519 - rebuild liferay-doc-utils.jar for 6.1.x
DevGuide - 6.1.x  - Remove orphaned images.
Merge pull request #511 from jhinkey/remove-images-6.1.x

6.1.x - rebuilt util jar and removed DevGuide images