Create Env class

lib/chervil/env.rb

+module Chervil
+  class Env
+    def initialize(parent = {})
+      @data = parent
+    end
+
+    def get(name)
+      @data[name]
+    end
+
+    def set(name, value)
+      @data[name] = value
+    end
+  end
+end