Fixed #705 by not calling desc if ::Rake.application.last_comment is set.  This allows users to enter their own description for the Rake task.
Merge pull request #716 from DavidEGrayson/yard_pull_request_3

Fix #705 by not calling desc if ::Rake.application.last_comment is set
Merge branch 'master' of github.com:lsegal/yard