Replace env.output interface with an IO like object

lib/producer/core/actions/echo.rb

@@ -3,7 +3,7 @@ module Producer
     module Actions
       class Echo < Action
         def apply
-          env.output arguments.first
+          env.output.puts arguments.first
         end
       end
     end

lib/producer/core/actions/shell_command.rb

@@ -3,7 +3,7 @@ module Producer
     module Actions
       class ShellCommand < Action
         def apply
-          env.output env.remote.execute(arguments.first)
+          env.output.puts env.remote.execute(arguments.first)
         end
       end
     end

lib/producer/core/env.rb

@@ -1,18 +1,13 @@
 module Producer
   module Core
     class Env
-      attr_writer   :output
-      attr_accessor :target
+      attr_accessor :output, :target
 
-      def initialize
-        @output = $stdout
+      def initialize(output: $stdout)
+        @output = output
         @target = nil
       end
 
-      def output(str)
-        @output.puts str
-      end
-
       def remote
         @remote ||= Remote.new(target)
       end