add /api/projects endpoint and /projects page with GH-style repo cards

layouts/_default/projects.html

@@ -0,0 +1,11 @@
+{{ define "main" }}
+<div class="layout layout-projects">
+  <h1><a class="no-underline" href="{{ .Permalink }}">{{ .Title | markdownify }}</a></h1>
+
+  <div id="content">
+    <div id="github-cards"></div>
+
+    <p><a href="https://github.com/jakejarvis?tab=repositories" target="_blank" rel="noopener">View more on GitHub...</a></p>
+  </div>
+</div>
+{{ end }}