add links for the funding campaign in the header and sidebar

doc/en/_templates/layout.html

@@ -1,5 +1,14 @@
 {% extends "!layout.html" %}
-
+{% block header %}
+<div align="center" xmlns="http://www.w3.org/1999/html">
+  <h4>
+    <a href="https://www.indiegogo.com/projects/python-testing-sprint-mid-2016#/">
+      Support the future of py.test join or fund the sprint in june
+    </a>
+  </h4>
+</div>
+  {{super()}}
+{% endblock %}
 {% block footer %}
 {{ super() }}
 <script type="text/javascript">

doc/en/_templates/links.html

@@ -1,5 +1,10 @@
 <h3>Useful Links</h3>
 <ul>
+  <li>
+    <a href="https://www.indiegogo.com/projects/python-testing-sprint-mid-2016#/">
+      <b>Sprint funding campaign</b>
+    </a>
+  </li>
   <li><a href="{{ pathto('index') }}">The pytest Website</a></li>
   <li><a href="{{ pathto('contributing') }}">Contribution Guide</a></li>
   <li><a href="https://pypi.python.org/pypi/pytest">pytest @ PyPI</a></li>