Send notifications to partecipants in issue comments (#1217)

* Send notifications to partecipants in issue comments

Closes #1216

Includes test (still failing)

* Do not include "labelers" to participants

Fix test to expect what GetParticipants return

models/fixtures/comment.yml

@@ -2,6 +2,18 @@
   id: 1
   type: 7 # label
   poster_id: 2
-  issue_id: 1
+  issue_id: 1 # in repo_id 1
   label_id: 1
   content: "1"
+-
+  id: 2
+  type: 0 # comment
+  poster_id: 3 # user not watching (see watch.yml)
+  issue_id: 1 # in repo_id 1
+  content: "good work!"
+-
+  id: 3
+  type: 0 # comment
+  poster_id: 5 # user not watching (see watch.yml)
+  issue_id: 1 # in repo_id 1
+  content: "meh..."

models/fixtures/issue.yml

@@ -8,7 +8,7 @@
   content: content1
   is_closed: false
   is_pull: false
-  num_comments: 0
+  num_comments: 2
   created_unix: 946684800
   updated_unix: 978307200