title: Admin Breaks When Using Jinja2
body: <p>For some reason my wagtail admin interface is breaking when I try and use Jinja2 as my template engine instead of Django Template Engine. My frontend works just fine, it finds my templates in app/jinja2. This is a Django project with wagtail added on.</p>
  
  <p>Here is the error that I am getting when trying to access /admin,</p>
  
  <pre><code>TemplateDoesNotExist at /admin/wagtailadmin/home.html
  Request Method: GET
  Request URL:    http://127.0.0.1:8000/admin/
  Django Version: 1.11
  Exception Type: TemplateDoesNotExist
  Exception Value: wagtailadmin/home.html
  Exception Location: /Users/dbroadlick/Desktop/projects/codero2/virtualenv/lib/python3.6/site-packages/django/template/loader.py in get_template, line 25
  Python Executable:  /Users/dbroadlick/Desktop/projects/codero2/virtualenv/bin/python
  Python Version: 3.6.1
  Python Path:    ['/Users/dbroadlick/Desktop/projects/codero2',
   '/Users/dbroadlick/Desktop/projects/codero2/virtualenv/lib/python36.zip',
   '/Users/dbroadlick/Desktop/projects/codero2/virtualenv/lib/python3.6',
   '/Users/dbroadlick/Desktop/projects/codero2/virtualenv/lib/python3.6/lib-dynload',
   '/Users/dbroadlick/Desktop/projects/codero2/virtualenv/lib/python3.6/site-packages']
  Server time:    Mon, 24 Jul 2017 21:40:59 +0000
  </code></pre>
  
  <p>Here is what my template configuration looks like,</p>
  
  <pre><code>TEMPLATES = [
  {
      'BACKEND': 'django.template.backends.jinja2.Jinja2',
      'APP_DIRS': True,
      'OPTIONS': {
          'extensions': [
              'wagtail.wagtailcore.jinja2tags.core',
              'wagtail.wagtailadmin.jinja2tags.userbar',
              'wagtail.wagtailimages.jinja2tags.images',
          ],
          'context_processors': [
              'django.template.context_processors.debug',
              'django.template.context_processors.request',
              'django.contrib.auth.context_processors.auth',
              'django.contrib.messages.context_processors.messages',
          ],
      },
  },
  ]
  </code></pre>
  
  <p>It also says it is trying to use the jinja2 engine which it should not because wagtail admin is programmed using Django templates.</p>