Decrease the amount of node saves

Fix multiline comment
Fix array initialization (was mistakenly initializing as a hash)

Author: scottwulf

chef/cookbooks/ceph/recipes/mon.rb

@@ -88,6 +88,7 @@
       add_key.error!
 
       # no need to check if the attribute is already set: it's part of the
+      # only_if
       node.set["ceph"]["monitor-secret"] = monitor_key
       node.save
     end

chef/cookbooks/ceph/recipes/osd.rb

@@ -71,7 +71,7 @@
   if is_crowbar?
     dirty = false
 
-    node.set["ceph"]["osd_devices"] ||= []
+    node.set["ceph"]["osd_devices"] = [] if node["ceph"]["osd_devices"].nil?
     min_size_blocks = node["ceph"]["osd"]["min_size_gb"] * 1024 * 1024 * 2
     unclaimed_disks = BarclampLibrary::Barclamp::Inventory::Disk.unclaimed(node).sort.select { |d| d.size >= min_size_blocks }