message: make the theme more dynamic
  don't hardcode the twitter handle
  default meta description if a summary isn't set
diff: <!-- Twitter and Facebook OpenGraph Metadata-->
  <meta name="twitter:card" content="summary_large_image" />
  - <meta name="twitter:site" content="@fluidframework" />
  + <meta name="twitter:site" content="@{{.Site.Params.twitterHandle}}" />
  <meta itemprop="datePublished" content="{{ now.Format "2006-01-02" }}">
  <!-- sections.meta -->
  {{ $summary := .Params.summary | plainify | truncate 140 }}
  + {{ if eq $summary ""}}
  + {{ $summary = .Title }}
  + {{ end }}
  <link rel="apple-touch-icon" sizes="180x180" href="/apple-touch-icon.png">
  <link rel="icon" type="image/png" sizes="32x32" href="/favicon-32x32.png">
  <link rel="icon" type="image/png" sizes="16x16" href="/favicon-16x16.png">
  <!-- EU Cookie Compliance CSS -->
  <link rel="stylesheet" href="//uhf.microsoft.com/mscc/statics/mscc-0.3.6.min.css">
  <!--Fabric CSS-->
  - <link rel="stylesheet" href="https://static2.sharepointonline.com/files/fabric/office-ui-fabric-core/11.0.0/css/fabric.min.css">
  + <link rel="stylesheet"
  + href="https://static2.sharepointonline.com/files/fabric/office-ui-fabric-core/11.0.0/css/fabric.min.css">
  {{ $style := resources.Get "scss/style.scss" | resources.ExecuteAsTemplate "css/style.css" . | toCSS | minify | fingerprint -}}
  <link rel="stylesheet" href="{{ $style.Permalink | relURL }}"
  