simple renaming ForeignKey between submit_milestones and review_milestones since submit_milestones should only have one review_milestone

also, the current tasks/views.py will not work without this change
rewrote code to take into account the fact that submit_milestones can have one and only one review_milestone
minor display beautifications
fixed broken dashboard link. you may not want to pull this to the production server, however, since the volunteer feature isn't fully complete
added permissions to view_all_chunks
minor code beautification
add permissions and catch DoesNotExist exceptions
commenting out CHUNKS_PER_ROLE because it's never used