Add "get_post_comments" support

Author: ivankravets

linkedin/linkedin.py

@@ -263,6 +263,16 @@ def get_posts(self, group_id, post_ids=None, selectors=None, params=None,
         response = self.make_request('GET', url, params=params, headers=headers)
         raise_for_error(response)
         return response.json()
+        
+    def get_post_comments(self, post_id, selectors=None, params=None,
+                  headers=None):
+        url = '%s/%s/comments' % (ENDPOINTS.POSTS, post_id)
+        if selectors:
+            url = '%s:(%s)' % (url, LinkedInSelector.parse(selectors))
+
+        response = self.make_request('GET', url, params=params, headers=headers)
+        raise_for_error(response)
+        return response.json()        
 
     def join_group(self, group_id):
         url = '%s/~/group-memberships/%s' % (ENDPOINTS.PEOPLE, str(group_id))