Always return qualified variable '::acpid_version'

This change will fix the facter acpid_version to return an
empty value if acpid not installed yet.

Change-Id: Ia85d73abf8591058c3dcf351d693f816b4d557eb
Closes-Bug: #1574674
Signed-off-by: Maksim Malchuk <mmalchuk@mirantis.com>

deployment/puppet/fuel/lib/facter/acpid_version.rb

@@ -3,6 +3,6 @@ require 'facter'
 Facter.add('acpid_version') do
   setcode do
     version = Facter::Util::Resolution.exec('acpid -v 2>/dev/null')
-    version.split('-')[1][0] unless version.nil?
+    version.nil? ? "" : version.split('-')[1][0]
   end
 end