(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.
This sounds like a good idea, the only problem is that we are relying on the package manager automatically installing the latest detected version of puppetserver which at this point is the development version which is set up in https://github.com/puppetlabs/puppet-server/blob/master/acceptance/suites/pre_suite/foss/30_install_dev_repos.rb

I'll experiment with detecting the currently installed version prior to removing, saving that in a variable, and attempting to re-install even if it's not the latest version.