switch to grunt-css-flip for RTL CSS generation

grunt/tasks/css-flip.js

@@ -1,27 +0,0 @@
-/*!
- * Bootstrap Grunt task for generating RTL CSS from LTR CSS using css-flip
- * http://getbootstrap.com
- * Copyright 2014 Twitter, Inc.
- * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
- */
-'use strict';
-
-var flip = require('css-flip');
-
-
-module.exports = function(grunt) {
-  grunt.registerMultiTask('cssFlip', 'Generates RTL CSS from LTR CSS using css-flip', function () {
-    this.files.forEach(function (f) {
-      var unflippedCss = grunt.file.read(f.src);
-      var flippedCss = null;
-      try {
-        flippedCss = flip(unflippedCss);
-      }
-      catch (err) {
-        grunt.fail.warn(err);
-      }
-      grunt.file.write(f.dest, flippedCss);
-      grunt.log.writeln('File ' + f.dest.cyan + ' created.');
-    });
-  });
-};