Clean imports in code

In some part in the code we import objects. In the Openstack style guidelines
they recommend to import only modules. [1]: "Do not import objects, only modules".

[1] https://docs.openstack.org/hacking/0.10.3/

Change-Id: I49452e41f9674e6ebfcc1577d59d21750e957677

sitemap/generator/spiders/sitemap_file.py

@@ -18,7 +18,7 @@ except ImportError:
     import urllib.parse as urlparse
 
 from scrapy import item
-from scrapy.linkextractors import LinkExtractor
+from scrapy import linkextractors
 from scrapy import spiders
 
 
@@ -43,7 +43,7 @@ class SitemapSpider(spiders.CrawlSpider):
 
     rules = [
         spiders.Rule(
-            LinkExtractor(
+            linkextractors.LinkExtractor(
                 allow=[
                     r'.*\.html',
                     r'.*\.pdf',