Fixes and features to allow plugin and config management

  * Add custom define to install plugins
  * Change server density install to use conf.d
  * use yumrepo on redhat type systems
  * Use apt::source on debian type systems
  * Try to use hostname and fqdn to find the device
Merge branch 'master' of https://github.com/compete/puppet-serverdensity into pr-14
Limit checks to just fqdn if we're only using that
Merge pull request #19 from serverdensity/pr-14

Improved config/plugin management