Re-add stats buttons to front page

[peterkwells]

Need to re-add stats buttons when confidence/inference stats are available. Unused code below:

 <div class="home-cta">
      <h2><a href="/get-involved/add-an-address">Donate Address Data</a></h2>
      <p>Everyone who uses Open Addresses will benefit from every address donation. Collaborate with us and together we can create better address data that everyone can use.</p>
      <div class="home-cta-data-indicator"><span>X<em>m</em></span> UK addresses</div>  
    </div>
    <div class="home-cta">
      <h2><a href="/developers/apis-and-data">Open Addresses For Your Apps</a></h2>
      <p>Developers! We’re looking for exciting and interesting ways Open Addresses can be used in your app or service. Get started with our APIs.</p>
      <div class="home-cta-data-indicator"><span><em>nnnn</em></span> average confidence score</div>
    </div>
    <div class="home-cta">
      <h2><a href="/get-involved/trialists">Partnering with Open Addresses</a></h2>
      <p>There should be no barriers to accessing vital national data such as the list of UK addresses. Try Open Addresses within your organisation and begin the journey of using and publishing open data.</p>

[peterkwells]

@pezholio @pikesley see the div class="home-cta-data-indicator"

I took these out before putting up the new site but they were originally going to be home for some metrics.

Suggest starting with just one that has the total addresses (i.e. distilled + inferred)?