Added site setting.

templates/sites/settings.html

@@ -0,0 +1,21 @@
+<form method="POST" action="/sites/{{.site.ID}}/settings">
+  <p>
+    <label>Title</label>
+    <input type="text" name="title" value="{{.site.Title}}" />
+  </p>
+  <p>
+    <label>Theme</label>
+    <select name="theme">
+      {{range .themes}}
+        {{if eq .ID $.site.Theme}}
+          <option value="{{.ID}}" selected>{{.Name}}</option>
+        {{else}}
+          <option value="{{.ID}}">{{.Name}}</option>
+        {{end}}
+      {{end}}
+    </select>
+  </p>
+  <p>
+    <input type="submit" value="Save" />
+  </p>
+</form>