buttonize terraPulse splash

[bbest]

Icons misaligned and need buttonizing at landing splash page http://benbestphd.com/terrapulse/:

[bbest]

Following http://fontawesome.io/examples/#stacked...

Square

<h2><a href="https://bdbest.shinyapps.io/terrapulse-gui/">
  <span class="fa-stack fa-lg">
    <i class="fa fa-square fa-stack-2x"></i>
    <i class="fa fa-map-marker fa-stack-1x fa-inverse"></i>
  </span>
  Find a Place</a></h2>

<h2><a href="https://bdbest.shinyapps.io/terrapulse-dashboard/">
  <span class="fa-stack fa-lg">
    <i class="fa fa-square fa-stack-2x"></i>
    <i class="fa fa-line-chart fa-stack-1x fa-inverse"></i>
  </span>
  Get Pulse on a Place</a></h2>

Circle

<h2><a href="https://bdbest.shinyapps.io/terrapulse-gui/">
  <span class="fa-stack fa-lg">
    <i class="fa fa-circle fa-stack-2x"></i>
    <i class="fa fa-map-marker fa-stack-1x fa-inverse"></i>
  </span>
  Find a Place</a></h2>

<h2><a href="https://bdbest.shinyapps.io/terrapulse-dashboard/">
  <span class="fa-stack fa-lg">
    <i class="fa fa-circle fa-stack-2x"></i>
    <i class="fa fa-line-chart fa-stack-1x fa-inverse"></i>
  </span>
  Get Pulse on a Place</a></h2>

[bbest]