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/specializer.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+module Fission
+  CODE_PATH = '/userfunc/user'
+
+  module Specializer
+    def self.call(env)
+      load CODE_PATH
+      Rack::Response.new([], 201).finish
+    rescue
+      Rack::Response.new(['500 Internal Server Error'], 500, {}).finish
+    end
+  end
+end