(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.
I'm still wondering if it would make sense to add a "yum -y reinstall #{name}" after the above so that all of the original configuration content would be in place at the time the "upgrade" is performed.  The state of the installation after a reinstall would seem to be most like what it would in the real world prior to an upgrade and still allow for the configuration files to be updated to the content in the new package.