Correct git status for directories without changes

git does not report any status for empty directories, and it also does not
report any status for directories without any modified, untracked or ignored
files.

To correctly show the status, we need to check whether the directory is empty if
git did not report any status codes. When empty, show it as "untracked",
otherwise show the "no changes" check mark.

Fixes athityakumar#334.

lib/colorls/core.rb

@@ -248,12 +248,14 @@ def git_dir_info(path)
       modes = if path == '.'
                 Set.new(@git_status.values).flatten
               else
-                @git_status.fetch(path, nil)
+                @git_status[path]
               end
 
-      return Git.colored_status_symbols(modes, @colors) unless modes.nil?
-
-      '    '
+      if modes.empty? && Dir.empty?(File.join(@input, path))
+        '    '
+      else
+        Git.colored_status_symbols(modes, @colors)
+      end
     end
 
     def long_info(content)