finish the first version of patch_file

Rakefile

@@ -0,0 +1,32 @@
+begin
+  require 'bundler/setup'
+rescue LoadError
+  puts 'You must `gem install bundler` and `bundle install` to run rake tasks'
+end
+
+require 'rdoc/task'
+
+RDoc::Task.new(:rdoc) do |rdoc|
+  rdoc.rdoc_dir = 'rdoc'
+  rdoc.title    = 'patchfile'
+  rdoc.options << '--line-numbers'
+  rdoc.rdoc_files.include('README.rdoc')
+  rdoc.rdoc_files.include('lib/**/*.rb')
+end
+
+
+
+
+Bundler::GemHelper.install_tasks
+
+require 'rake/testtask'
+
+Rake::TestTask.new(:test) do |t|
+  t.libs << 'lib'
+  t.libs << 'test'
+  t.pattern = 'test/**/*_test.rb'
+  t.verbose = false
+end
+
+
+task default: :test