Show actual version in topbar instead of hardcoded beta (Fixes #93)

internal/web/templates/layout.html

@@ -13,7 +13,7 @@
 
 {{define "topbar"}}
   <div class="topbar">
-    <a class="logo" href="/history">Palette <em>/ beta</em></a>
+    <a class="logo" href="/history">Palette <em>/ {{ version }}</em></a>
     <nav>
       <a href="/new" {{if eq .Page "new"}}class="on"{{end}}>New</a>
       <a href="/history" {{if eq .Page "history"}}class="on"{{end}}>Public</a>