Added preview and sections fields to LMS Topic

- The preview is used to show the details of the topic in the course page
- the sections are used to show the different part of the topic, each could be of a different type

Issue #8

community/www/courses/course.py

@@ -17,7 +17,7 @@ def get_course(name):
 		filters={
 			'course': name
 		},
-		fields=['name', 'title', 'description'],
+		fields=['name', 'title', 'preview'],
 		order_by='creation'
 	)
 	return course