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/handler.rb

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+require_relative 'context'
+
+module Fission
+  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