(PUP-1977) Update puppet module generate to create metadata.json

Prior to this commit, running `puppet module generate` would create a Modulefile with the appropriate metadata, from which a metadata.json file would be generated when you ran `puppet module build`.  Since we're migrating away from the Modulefile as the canonical source of metadata (as per PE-3117), this commit will instead generate an equivalent metadata.json file when the module is created.

lib/puppet/module_tool/applications/generator.rb

@@ -8,7 +8,21 @@ class Generator < Application
 
       def initialize(full_module_name, options = {})
         begin
-          @metadata = Metadata.new.update('name' => full_module_name, 'version' => '0.0.1')
+          @metadata = Metadata.new.update(
+            'name' => full_module_name,
+            'version' => '0.0.1',
+            'dependencies' => [
+              { :name => 'puppetlabs-stdlib', :version_range => '>= 1.0.0' }
+            ]
+          )
+
+          # These are used in the generation of the metadata.json file t
+          # simulate an ordered hash.  In particular, the keys listed below are
+          # promoted to the top of the serialized hash for human-friendliness.
+          #
+          # This particularly works around the lack of ordered hashes in 1.8.7.
+          @hash = @metadata.to_hash
+          @remaining_keys = @hash.keys - %w[ name version author summary license source ]
         rescue ArgumentError
           msg = "Could not generate directory #{full_module_name.inspect}, you must specify a dash-separated username and module name."
           raise $!, msg, $!.backtrace

lib/puppet/module_tool/skeleton/templates/generator/metadata.json.erb

@@ -0,0 +1,9 @@
+{
+  "name": <%= @hash['name'].to_json %>,
+  "version": <%= @hash['version'].to_json %>,
+  "author": <%= @hash['author'].to_json %>,
+  "summary": <%= @hash['summary'].to_json %>,
+  "license": <%= @hash['license'].to_json %>,
+  "source": <%= @hash['source'].to_json %>,
+<%= @remaining_keys.map { |k| "#{k.to_json}: #{PSON.pretty_generate(@hash[k])}" }.join(",\n").gsub(/^/, '  ') %>
+}