added Date and URL to DESCRIPTION

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/gridgraph@43 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
bumped Ashley up to Author

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/gridgraph@44 edb9625f-4e0d-4859-8d74-9fd3b1da38cb