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/request.rb

@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+module Fission
+  HEADER_PREFIX = 'HTTP_'
+  PARAM_HEADER_PREFIX = 'HTTP_X_FISSION_PARAMS_'
+  PARAMETERS_KEY = 'fission.request.parameters'
+
+  class Request < Rack::Request
+    def headers
+      Hash[
+        *env.select { |k,v| k.start_with?(HEADER_PREFIX) }
+             .map { |k,v| [k.sub(/\A#{HEADER_PREFIX}/, '').split('_').map(&:capitalize).join('-'), v] }
+             .sort
+             .flatten
+      ]
+    end
+
+    def params
+      env[PARAMETERS_KEY] ||= super.merge(path_parameters)
+    end
+
+    def path_parameters
+      Hash[
+        *env.select { |k,v| k.start_with?(PARAM_HEADER_PREFIX) }
+             .map { |k,v| [k.sub(/\A#{PARAM_HEADER_PREFIX}/, '').downcase, v] }
+             .sort
+             .flatten
+      ]
+    end
+  end
+end