add a Rake task to release the project

Rakefile

@@ -0,0 +1,24 @@
+desc "create a new release"
+task 'release' do
+  current_version = run('git tag').split(/\n/).last.strip
+  puts "What version do you want to release? (current: #{current_version})"
+  version = STDIN.gets.strip
+  version_tag = "v%s" % version
+
+  if run('git tag').split(/\n/).include?(version_tag)
+    raise("This tag has already been committed to the repo.")
+  end
+
+  rbenv_contents = File.read('rbenv.el')
+  File.write('rbenv.el', rbenv_contents.gsub("Version: #{current_version}", "Version: #{version}"))
+
+  run "git commit -a -m \"prepare #{version}\""
+
+  run "git tag -a -m \"Version #{version}\" #{version_tag}"
+  run "git push origin"
+  run "git push origin --tags"
+end
+
+def run(command)
+  `#{command}`
+end