Implement basic Remote::Environment class:

Represent a registry for remote environment variables, will follow an
API similar to Hash except the constructor. Currently only #has_key? is
implemented.

lib/producer/core/remote/environment.rb

@@ -0,0 +1,27 @@
+module Producer
+  module Core
+    class Remote
+      class Environment
+        require 'forwardable'
+
+        extend Forwardable
+        def_delegator :@variables, :has_key?
+
+        def initialize(variables)
+          case variables
+          when String
+            @variables = parse_from_string variables
+          else
+            @variables = variables
+          end
+        end
+
+        private
+
+        def parse_from_string(str)
+          Hash[str.each_line.map { |l| l.chomp.split '=', 2 }]
+        end
+      end
+    end
+  end
+end