(SERVER-256) Fix failing FOSS upgrade smoke test.

* This adds a method, package_upgrade, which always upgrades the given package
  regardless of whether there are changes both to the new version of the config
  file and to the previously-installed version.
* Also removes the puppet_server_name parameter on install_puppet_server which
  is unnecessary since as it turns out there is only actually one package name
  for puppet_server.
* Also removes some completely dead code which attemptes to modify
  SERVICE_NUM_RETRIES in puppetserver's defaults file. This variable is no
  longer used.
Actually I just successfully smoke tested removing the changed configuration files using `rm -f $(rpm --verify puppetserver | cut -f 4)` then running `yum -y upgrade` to get up to the latest development version. Will update this PR shortly.