[simple theme] replace Image_layout.js with flexbox CS impl.

* drop image_layout.js from simple theme
* move image_layout.js to oscar theme and delete common js dir (since its empty now)
* align top position of image detail modal with bottom position of search header
* use flexbox to display images; row height can be set via @results-image-row-height in defenitions.less
* display span title underneath each image with a max width of 12rem
* increase margin and padding around image article on desktop and tablet
* make article height smaller on phone layout (height of 6rem) to display more content on current view
* remove content from result, if the title and content matches
* use a group that cotains the flex image article, if images are mixed with other categories
* fix pylint issues in webapp.py
* use the default.html result template in unit tests (thanks @return42)

searx/results.py

@@ -278,12 +278,18 @@ class ResultContainer:
             result['parsed_url'] = result['parsed_url']._replace(scheme="http")
             result['url'] = result['parsed_url'].geturl()
 
+        # avoid duplicate content between the content and title fields
+        if result.get('content') == result.get('title'):
+            del result['content']
+
+        # make sure there is a template
+        if 'template' not in result:
+            result['template'] = 'default.html'
+
         # strip multiple spaces and cariage returns from content
         if result.get('content'):
             result['content'] = WHITESPACE_REGEX.sub(' ', result['content'])
 
-        return True
-
     def __merge_url_result(self, result, position):
         result['engines'] = set([result['engine']])
         with self._lock: