Git ignore file

• Simple - From MichaelCurrin/jekyll-blog-demo

    .jekyll-cache/
    .sass-cache/
    .jekyll-metadata
  
    .bundle/
    vendor/
  
    _site/
  

Notes:

• .jekyll-metadata - File is added when running jekyll new PATH or serving in incremental mode.
• .bundle/ - Stores the Bundler config. This can be different for local and prod/remote deploys when packages are frozen, so do not version. See the Bundler install docs about using --deployment and --frozen flags which probably change this.