Cookbook attempts to download sources even when package is installed

[jgoldschrafe]

The cookbook attempts to download the collectd source even when the package is installed and the sources will not be built. This should be fixed by duplicating the guard clause from the resource that builds the sources onto the remote_file resource:

  not_if "#{node["collectd"]["dir"]}/sbin/collectd -h 2>&1 | grep #{node["collectd"]["version"]}"

[hectcastro]

Hey @jgoldschrafe, would you mind submitting that as a pull request? If so, I'll try to review it over the weekend.