don't try to attach packages in the current R session, because it will be very difficult to cleanly detach the package

e.g. we might get erros like this even if the package is loadable

Error in dyn.load(file, DLLpath = DLLpath, ...) :
  unable to load shared object '/home/travis/R/goftest/libs/goftest.so':
  `maximal number of DLLs reached...
see if I can suppress the messages of the form

Creating config file /etc/texmf/texmf.d/05TeXMF.cnf with new version
more jobs in the knitr matrix