title: Angular 5 with Bootstrap 4 not working
body: <p>I created a new Angular 5 project. After that I followed instructions given on <a href="https://github.com/angular/angular-cli/wiki/stories-include-bootstrap" rel="noreferrer">Angular CLI GitHub page</a>
  to use Bootstrap 4.0.0 with Angular 5.2.2. I use 'npm install bootstrap' to install bootstrap. but I get...</p>
  
  <pre><code>Unknown error from PostCSS plugin. Your current PostCSS version is 
  6.0.15, but autoprefixer uses 5.2.18. Perhaps this is the source of 
  the error below.
  ...
  ...
  ERROR in ./node_modules/css-loader?
  {"sourceMap":false,"importLoaders":1}!./node_modules/postcss-
  loader/lib{"ident":"postcss","sourceMap":false}!./node_modules/bootstrap/
  dist/css/bootstrap.min.css
  Module build failed: BrowserslistError: Unknown browser major
  ...
  ...
  webpack: Failed to compile.
  </code></pre>