refactor: step-down rule

Present methods in roughly the same order as they are referenced,
to make it more graceful to read without jumping back and forth.

lib/paperclip/content_type_detector.rb

@@ -39,26 +39,26 @@ module Paperclip
 
     private
 
-    def empty_file?
-      File.exist?(@filepath) && File.size(@filepath) == 0
-    end
-
-    alias :empty? :empty_file?
-
     def blank_name?
       @filepath.nil? || @filepath.empty?
     end
 
-    def possible_types
-      MIME::Types.type_for(@filepath).collect(&:content_type)
+    def empty_file?
+      File.exist?(@filepath) && File.size(@filepath) == 0
     end
 
+    alias :empty? :empty_file?
+
     def calculated_type_matches
       possible_types.select do |content_type|
         content_type == type_from_file_contents
       end
     end
 
+    def possible_types
+      MIME::Types.type_for(@filepath).collect(&:content_type)
+    end
+
     def type_from_file_contents
       type_from_mime_magic || type_from_file_command
     rescue Errno::ENOENT => e
@@ -66,14 +66,14 @@ module Paperclip
       SENSIBLE_DEFAULT
     end
 
-    def type_from_file_command
-      @type_from_file_command ||=
-        FileCommandContentTypeDetector.new(@filepath).detect
-    end
-
     def type_from_mime_magic
       @type_from_mime_magic ||=
         MimeMagic.by_magic(File.open(@filepath)).try(:type)
     end
+
+    def type_from_file_command
+      @type_from_file_command ||=
+        FileCommandContentTypeDetector.new(@filepath).detect
+    end
   end
 end