Apply fixes suggested by Rubocop.

lib/homesick.rb

@@ -1,4 +1,3 @@
-# -*- encoding : utf-8 -*-
 require 'homesick/actions/file_actions'
 require 'homesick/actions/git_actions'
 require 'homesick/version'
@@ -7,8 +6,8 @@ require 'homesick/cli'
 
 # Homesick's top-level module
 module Homesick
-  GITHUB_NAME_REPO_PATTERN = %r{\A([A-Za-z0-9_-]+/[A-Za-z0-9_-]+)\Z}
-  SUBDIR_FILENAME = '.homesick_subdir'
+  GITHUB_NAME_REPO_PATTERN = %r{\A([A-Za-z0-9_-]+/[A-Za-z0-9_-]+)\Z}.freeze
+  SUBDIR_FILENAME = '.homesick_subdir'.freeze
 
-  DEFAULT_CASTLE_NAME = 'dotfiles'
+  DEFAULT_CASTLE_NAME = 'dotfiles'.freeze
 end