Creates a bash script to update the system to satisfy project requirements.
build_bash_script(recipe, plat_desc)
object of type sysreqs_script_recipe
named list content:
One of Windows, MacOS, RedHat, Debian (type: character)
Distribution e.g. for Debian: Debian, Ubuntu; for RedHat: CentOS, RedHat, Fedora (type: character(1))
Distribution release e.g. for Debian: squeeze, wheezy, jessie (type: character(1))
One of Windows, Pkg, RPM, DEB (type: character(1))
True if build environment is required (type: logical(1))