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/server.rb

@@ -1,55 +1,9 @@
 # frozen_string_literal: true
+
 require 'rack'
 
-CODEPATH = '/userfunc/user'
-
-module Fission
-  class Request < Rack::Request
-    def headers
-      Hash[
-        *env.select { |k,v| k.start_with?('HTTP_') }
-             .map { |k,v| [k.sub(/\AHTTP_/, '').split('_').map(&:capitalize).join('-'), v] }
-             .sort
-             .flatten
-      ]
-    end
-  end
-
-  class Context
-    attr_reader :env
-
-    def initialize(env)
-      @env = env
-    end
-
-    def request
-      @request ||= Request.new(env)
-    end
-  end
-
-  module Specializer
-    def self.call(env)
-      load CODEPATH
-      Rack::Response.new([], 201).finish
-    rescue
-      Rack::Response.new(['500 Internal Server Error'], 500, {}).finish
-    end
-  end
-
-  module Handler
-    def self.call(env)
-      response = if method(:handler).arity > 0
-        handler(Context.new(env))
-      else
-        handler
-      end
-
-      response.is_a?(Array) ? response : Rack::Response.new([response]).finish
-    rescue
-      Rack::Response.new(['500 Internal Server Error'], 500, {}).finish
-    end
-  end
-end
+require_relative 'fission/specializer'
+require_relative 'fission/handler'
 
 app = Rack::Builder.new do
   use Rack::CommonLogger, $stderr