Remove headers already set in GitLab application_controller.rb
Move Unicorn settings to doc/settings/unicorn.md
Move SMTP settings to doc/settings/smtp.md
Add doc/settings/README.md
Document the existence of `gitlab-ci-rake`
Document the existence of `gitlab-ci-rails`
Merge branch 'master' into 'master'

Prevent HTTP Headers Being Sent Twice In Responses

The nginx conf adds three security headers that are already set in the GitLab application_controller, as shown at the following URL:

https://gitlab.com/gitlab-org/gitlab-ce/blob/master/app/controllers/application_controller.rb#L162

This results in the headers being sent twice, as shown below:

wget --server-response --spider --no-check-certificate https://127.0.0.1
```
HTTP/1.1 200 OK
  Server: nginx
  Date: Wed, 29 Oct 2014 08:53:57 GMT
  Content-Type: text/html; charset=utf-8
  Connection: keep-alive
  Status: 200 OK
  X-Frame-Options: DENY
  X-XSS-Protection: 1; mode=block
  X-Content-Type-Options: nosniff
  X-UA-Compatible: IE=edge
  Strict-Transport-Security: max-age=31536000
  ETag: "5bdf7a2806e69e538a1ff3ea60e2cf92"
  Cache-Control: max-age=0, private, must-revalidate
  Set-Cookie: _gitlab_session=34dc882bfa6fd21dfde1651d9c6847ce; path=/; expires=Wed, 05 Nov 2014 08:53:57 -0000; secure; HttpOnly
  X-Request-Id: f04beca7-114e-4fa9-9a8d-73f153dc349f
  X-Runtime: 0.013610
  Strict-Transport-Security: max-age=63072000
  X-Frame-Options: SAMEORIGIN
  X-Content-Type-Options: nosniff
```

This issue affects the latest version of GitLab (7.4.2-omnibus-1).

See merge request !233
Merge branch 'doc/ci' into 'master'

Add some documentation for GitLab CI settings

See merge request !235
Improved update doc, with new remarks about downgrade
Fixed markdown
Fixed markdown of update process to look friendlier.
Removed extra #
Added Reconfigure Title
Merge branch 'improve_update_doc' into 'master'

Improve update Documenation

Improved the update documentation to be more readable and to include a hint that the `dropdb` command is only necessary if downgrading to version older than 6.8.0

See merge request !6