Fixed imports in `Sitemap for static views` example

    # sitemaps.py

    from django.contrib import sitemaps

    from django.contrib.sitemaps.views import sitemap

    from django.core.urlresolvers import reverse

    from . import views

    class StaticViewSitemap(sitemaps.Sitemap):

        priority = 0.5

        changefreq = 'daily'

    # urls.py

    from django.conf.urls import url

    from django.contrib.sitemaps.views import sitemap

    from .sitemaps import StaticViewSitemap

    from . import views

    sitemaps = {

        'static': StaticViewSitemap,