Strip Rakefile of custom tasks and rely on standard bundler/gem_tasks

Rakefile

@@ -1,44 +1,4 @@
-def version
-  @version ||= begin
-    plist = File.expand_path('../../Terminal Notifiers/notify/Terminal Notifier/Terminal Notifier-Info.plist', __FILE__)
-    `/usr/libexec/PlistBuddy -c 'Print :CFBundleShortVersionString' '#{plist}'`.strip
-  end
-end
-
-def types
-  %w(notify success pending failed)
-end
-
-def type_file_name(type)
-  "tn_#{type}-#{version}"
-end
-
-def filenames
-  types.map{|type| type_file_name(type)}
-end
-
-def zip_file_name(type)
-  "#{type_file_name(type)}.zip"
-end
-
-def zipfiles
-  types.map{|n| zip_file_name(n)}
-end
-
-task :clean do
-  rm zipfiles
-  rm_rf "vendor"
-end
-
-desc "Update the vendored terminal notifiers."
-task :update_build do
-  puts "This needs fixing."
-end
-
-desc "Build gem"
-task :gem => :update_build do
-  sh "gem build terminal-notifier-guard.gemspec"
-end
+require "bundler/gem_tasks"
 
 desc "Run specs"
 task :spec do