fix(@angular/cli): update autoprefixer

Fix #9020, related to https://travis-ci.org/angular/angular-cli/jobs/322676874#L3792

Author: filipesilva

package-lock.json

@@ -44,7 +44,7 @@
     "@angular-devkit/build-optimizer": "~0.0.36",
     "@angular-devkit/schematics": "~0.0.42",
     "@schematics/angular": "~0.1.11",
-    "autoprefixer": "^6.5.3",
+    "autoprefixer": "^7.2.3",
     "chalk": "~2.2.0",
     "circular-dependency-plugin": "^4.2.1",
     "common-tags": "^1.3.1",

package.json

@@ -32,7 +32,7 @@
     "@ngtools/json-schema": "1.1.0",
     "@ngtools/webpack": "1.9.3",
     "@schematics/angular": "~0.1.11",
-    "autoprefixer": "^6.5.3",
+    "autoprefixer": "^7.2.3",
     "chalk": "~2.2.0",
     "circular-dependency-plugin": "^4.2.1",
     "common-tags": "^1.3.1",

packages/@angular/cli/package.json

@@ -6,7 +6,7 @@ import {oneLineTrim} from 'common-tags';
 
 export default function() {
   return Promise.resolve()
-    .then(() => silentNpm('install', 'bootstrap@next'))
+    .then(() => silentNpm('install', 'bootstrap@4.0.0-beta.3'))
     .then(() => updateJsonFile('.angular-cli.json', configJson => {
       const app = configJson['apps'][0];
       app['styles'].push('../node_modules/bootstrap/dist/css/bootstrap.css');