just keep all fields
use update.packages() to ensure R 2.x packages are updated
update branch Thu Oct  2 02:29:02 CDT 2014
update branch knitr Thu Oct  2 13:02:26 CDT 2014
update branch knitr Thu Oct  2 14:49:45 CDT 2014
update branch knitr Thu Oct  2 19:41:50 CDT 2014