Implement recipe arguments

CLI will stop arguments processing after the special `--' argument,
the rest will be saved in the env and accessible through a new task
keyword: `recipe_argv'.

lib/producer/core/env.rb

@@ -5,7 +5,7 @@ module Producer
       def_delegators :@registry, :[]=, :key?
 
       attr_reader   :input, :output, :error_output, :registry, :logger
-      attr_accessor :target, :verbose, :debug, :dry_run
+      attr_accessor :target, :verbose, :debug, :dry_run, :recipe_argv
 
       def initialize(input: $stdin, output: $stdout, error_output: $stderr, remote: nil, registry: {})
         @verbose = @debug = @dry_run = false