include path parameters in params hash for ruby environment (#249)

* include path parameters in params hash for ruby environment

* Improve code organization and documentation for ruby environment.

* Document Ruby examples

environments/ruby/fission/context.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+require_relative 'request'
+
+module Fission
+  class Context
+    attr_reader :env
+
+    def initialize(env)
+      @env = env
+    end
+
+    def request
+      @request ||= Request.new(env)
+    end
+  end
+end