Use a password attribute in the parity_node resource

The mainnet and testnet nodes use data from an encrypted data bag

Also fix a bug with the resource (hardcoded "dev" name instead of the
name attribute)

site-cookbooks/kosmos-parity/recipes/node_mainnet.rb

@@ -7,7 +7,10 @@
 # All rights reserved - Do Not Redistribute
 #
 
+credentials = Chef::EncryptedDataBagItem.load('credentials', 'parity')
+
 parity_node "mainnet" do
+  password credentials["mainnet_password"]
   config parity: {
            chain: "homestead",
          },