Create separate steps for Install and Prepare

Currently there is on the "install_packages" boolean, which when set to true causes all of the required packages to be installed and prepared/configured. In order to make some benchmarks work I have had to pre-install and set "install_packages" to false. The most difficult part is the prepare or configure step which can require making folders in /tmp/pkb/ and copying programs and config files. This is made more difficult because the /tmp folder is deleted at every reboot.
I suggest adding a separate "prepare_packages" flag. Then with "install_packages"=false and "prepare_packages"=true you could pre-install the software, but the benchmark's scripts would do the preparation/configuration.