Add attributes to choose whether to install graphical UI or not

It might not make sense to install that for everyone, so make this an
option disabled by default.

attributes/default.rb

@@ -19,7 +19,7 @@ when 'suse'
 
   # pacemaker-mgmt-client provides hb_gui, which it's useful
   # to run over ssh.
-  default[:pacemaker][:platform][:packages] += %w(
+  default[:pacemaker][:platform][:graphical_packages] = %w(
     pacemaker-mgmt-client xorg-x11-xauth
   )
 else

recipes/default.rb

@@ -22,13 +22,19 @@ node[:pacemaker][:platform][:packages].each do |pkg|
   package pkg
 end
 
-# required to run hb_gui
-if platform_family? "suse"
-  cmd = "SuSEconfig --module gtk2"
-  execute cmd do
-    user "root"
-    command cmd
-    not_if { File.exists? "/etc/gtk-2.0/gdk-pixbuf64.loaders" }
+if node[:pacemaker][:setup_hb_gui]
+  node[:pacemaker][:platform][:graphical_packages].each do |pkg|
+    package pkg
+  end
+
+  # required to run hb_gui
+  if platform_family? "suse"
+    cmd = "SuSEconfig --module gtk2"
+    execute cmd do
+      user "root"
+      command cmd
+      not_if { File.exists? "/etc/gtk-2.0/gdk-pixbuf64.loaders" }
+    end
   end
 end