adding ABS tests.

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/tsdbi@556 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
adding hasData utilities documentation.

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/tsdbi@557 edb9625f-4e0d-4859-8d74-9fd3b1da38cb