changed foo fxn name internally in pkgs_mran to get_pkg_versions
removing file with pkgs to install in pkgs_mran fxn, closes #88
pkgs_mran no longer longer generating PACKAGES and PACKAGES.gz files, closes #85
changed rrt_install and pkgs_mran to check for packages by listing files downloaded instead of PACKAGES file
fixed getPkgs so that when mran is FALSE, packages to get properly indexed
additionally, when mran is FALSE, src/contrib dir created now as it is indeed needed