Add @project variable to merge request emails

After this change project name appears in the top part of email when you
open/close/accept merge request.
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/mailers/emails/merge_requests.rb

@@ -2,23 +2,27 @@ module Emails
   module MergeRequests
     def new_merge_request_email(recipient_id, merge_request_id)
       @merge_request = MergeRequest.find(merge_request_id)
+      @project = @merge_request.project
       mail(to: recipient(recipient_id), subject: subject("New merge request ##{@merge_request.iid}", @merge_request.title))
     end
 
     def reassigned_merge_request_email(recipient_id, merge_request_id, previous_assignee_id)
       @merge_request = MergeRequest.find(merge_request_id)
       @previous_assignee = User.find_by_id(previous_assignee_id) if previous_assignee_id
+      @project = @merge_request.project
       mail(to: recipient(recipient_id), subject: subject("Changed merge request ##{@merge_request.iid}", @merge_request.title))
     end
 
     def closed_merge_request_email(recipient_id, merge_request_id, updated_by_user_id)
       @merge_request = MergeRequest.find(merge_request_id)
       @updated_by = User.find updated_by_user_id
+      @project = @merge_request.project
       mail(to: recipient(recipient_id), subject: subject("Closed merge request ##{@merge_request.iid}", @merge_request.title))
     end
 
     def merged_merge_request_email(recipient_id, merge_request_id)
       @merge_request = MergeRequest.find(merge_request_id)
+      @project = @merge_request.project
       mail(to: recipient(recipient_id), subject: subject("Accepted merge request ##{@merge_request.iid}", @merge_request.title))
     end
   end