Send notification emails to the "project", and put people in Cc

This fixes email threading in Mail.app, that doesn't like when a thread
doesn't have stable recipients.

For instance, here is a possible sender-recipient combinations before:

From: A
To: Me
New issue

From: B
To: Me
Reply on new issue

From: A
To: Me
Another reply

Mail.app doesn't see B as a participant to the original email thread,
and decides to break the thread: it will group all messages from A
together, and separately all messages from B.

This commit makes the thread look like this:

From: A
To: gitlab/project
Cc: Me
New issue

From: B
To: gitlab/project
Cc: Me
Reply on new issue

From: A
To: gitlab/project
Cc: Me
Another reply

Mail.app sees a common recipient, and group the thread correctly.

1 files changed, 1 insertions, 1 deletions

diff --git a/spec/services/merge_requests/close_service_spec.rb b/spec/services/merge_requests/close_service_spec.rb
index a504f916b08..2c5a7c4f26c 100644
--- a/spec/services/merge_requests/close_service_spec.rb
+++ b/spec/services/merge_requests/close_service_spec.rb
@@ -22,7 +22,7 @@ describe MergeRequests::CloseService do
 
       it 'should send email to user2 about assign of new merge_request' do
         email = ActionMailer::Base.deliveries.last
-        email.to.first.should == user2.email
+        email.cc.first.should == user2.email
         email.subject.should include(merge_request.title)
       end