Add thumbnails in images results

- Modify engines to create/fetch an URL for the thumbnails
- Modify themes to show thumbnails instead of full images.

In Courgette, the result is not very beautiful. Should we change it ?

searx/engines/500px.py

@@ -14,6 +14,7 @@
 from urllib import urlencode
 from urlparse import urljoin
 from lxml import html
+import re
 
 # engine dependent config
 categories = ['images']
@@ -37,20 +38,25 @@ def response(resp):
     results = []
 
     dom = html.fromstring(resp.text)
+    regex = re.compile('3\.jpg.*$')
 
     # parse results
     for result in dom.xpath('//div[@class="photo"]'):
         link = result.xpath('.//a')[0]
         url = urljoin(base_url, link.attrib.get('href'))
         title = result.xpath('.//div[@class="title"]//text()')[0]
-        img_src = link.xpath('.//img')[0].attrib['src']
+        thumbnail_src = link.xpath('.//img')[0].attrib['src']
+        # To have a bigger thumbnail, uncomment the next line
+        #thumbnail_src = regex.sub('4.jpg', thumbnail_src)
         content = result.xpath('.//div[@class="info"]//text()')[0]
+        img_src = regex.sub('2048.jpg', thumbnail_src)
 
         # append result
         results.append({'url': url,
                         'title': title,
                         'img_src': img_src,
                         'content': content,
+                        'thumbnail_src': thumbnail_src,
                         'template': 'images.html'})
 
     # return results