add collection page with table of collections and update button

backstage/templates/collections.html

@@ -0,0 +1,31 @@
+{% extends "layout.html" %}
+{% block main %}
+<h1>規劃作品</h1>
+<table id="example" class="table table-striped table-bordered" cellspacing="0" width="60%">
+  <thead>
+    <tr>
+      <th>數量</th>
+      <th>標題</th>
+      <th>順序</th>
+      <th style="text-align:center;width:100px;">新增 <button type="button" data-func="dt-add" class="btn btn-success btn-xs dt-add">
+          <span class="glyphicon glyphicon-plus" aria-hidden="true"></span>
+        </button></th>
+    </tr>
+  </thead>
+{% for collection in collections %}
+    <tbody>
+      <tr>
+        <td>1</td>
+        <td>{{ collection.title }}</td>
+        <td>1</td>
+        <td>
+          <div>
+            <a class="btn btn-secondary btn-sm m-1" href="{{ url_for('editor.editor', url=collection.url) }}">編輯</a>
+            <a class="btn btn-secondary btn-sm m-1" href="#">刪除</a>
+          </div>
+        </td>
+      </tr>
+    </tbody>
+{% endfor %}
+</table>
+{% endblock main %}