fixed response variable names in bayesr.model.frame()

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/bayesr@856 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
use optimize2

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/bayesr@857 edb9625f-4e0d-4859-8d74-9fd3b1da38cb