Revert "Revert "Remove caTools dependency""

This reverts commit 8d4b9076f7df81ed6cde6141ae643618dc4fb40b.

The main concern for the previous reversion was the Glimmer/Spark servers (Rcpp requires R >= 3.0.0). We are able to install Rcpp/httpuv under R 2.15.3 (https://gist.github.com/yihui/43a68d811dade1d9e828), so it is possible to upgrade Rcpp/httpuv/shiny on Glimmer/Spark. On the other hand, we are going to shut down Glimmer/Spark by the end of this year anyway, and move to ShinyApps.io, which makes this R 3.x issue even less of concern.
add the R version requirement to NEWS
bump version