Build modified streamline images

The official image from streamline does not currently work for the arm64
platform. As a temporary measure, the source code and docker build scripts
have been lifted from the official images and are used to build locally.

Some additional modifications are made to reduce overall image size, these
are documented in docker/README.md

docker/streamline-src/public/elite/bootstrap/grunt/bs-raw-files-generator.js

@@ -0,0 +1,44 @@
+/*!
+ * Bootstrap Grunt task for generating raw-files.min.js for the Customizer
+ * http://getbootstrap.com
+ * Copyright 2014-2015 Twitter, Inc.
+ * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
+ */
+
+'use strict';
+
+var fs = require('fs');
+var btoa = require('btoa');
+var glob = require('glob');
+
+function getFiles(type) {
+  var files = {};
+  var recursive = type === 'less';
+  var globExpr = recursive ? '/**/*' : '/*';
+  glob.sync(type + globExpr)
+    .filter(function (path) {
+      return type === 'fonts' ? true : new RegExp('\\.' + type + '$').test(path);
+    })
+    .forEach(function (fullPath) {
+      var relativePath = fullPath.replace(/^[^/]+\//, '');
+      files[relativePath] = type === 'fonts' ? btoa(fs.readFileSync(fullPath)) : fs.readFileSync(fullPath, 'utf8');
+    });
+  return 'var __' + type + ' = ' + JSON.stringify(files) + '\n';
+}
+
+module.exports = function generateRawFilesJs(grunt, banner) {
+  if (!banner) {
+    banner = '';
+  }
+  var dirs = ['js', 'less', 'fonts'];
+  var files = banner + dirs.map(getFiles).reduce(function (combined, file) {
+    return combined + file;
+  }, '');
+  var rawFilesJs = 'docs/assets/js/raw-files.min.js';
+  try {
+    fs.writeFileSync(rawFilesJs, files);
+  } catch (err) {
+    grunt.fail.warn(err);
+  }
+  grunt.log.writeln('File ' + rawFilesJs.cyan + ' created.');
+};