add a R package to install

ansible_provisioning/files/install-r-packages.sh

@@ -35,6 +35,7 @@ echo "dir.create(Sys.getenv('R_LIBS_USER'), recursive=TRUE); \
   'testthat', \
   'Rcpp', \
   'RcppArmadillo', \
+  'RcppEigen', \
   'fasterize', \
   'roxygen2', \
   'shiny', \