Replace CLA with the DCO + License

gitlab-com/organization#146

CONTRIBUTING.md

+## Developer Certificate of Origin + License
+
+By contributing to GitLab B.V., You accept and agree to the following terms and
+conditions for Your present and future Contributions submitted to GitLab B.V.
+Except for the license granted herein to GitLab B.V. and recipients of software
+distributed by GitLab B.V., You reserve all right, title, and interest in and to
+Your Contributions. All Contributions are subject to the following DCO + License
+terms.
+
+[DCO + License](https://gitlab.com/gitlab-org/dco/blob/master/README.md)
+
+_This notice should stay as the first item in the CONTRIBUTING.md file._
+
+---
+
 # Contribution guidelines
-- [Contributor license agreement](#contributor-license-agreement)
 - [Contribute to GitLab](#contribute-to-gitlab)
 - [For wider community contributors :strawberry:](#for-wider-community-contributors-)
 - [For GitLabbers :fox:](#for-gitlabbers-)
@@ -13,19 +27,6 @@
 - [Git](#git)
 - [Code of conduct](#code-of-conduct)
-
-## Contributor license agreement
-
-By submitting code as an individual you agree to the [individual contributor
-license agreement][individual-agreement].
-
-By submitting code as an entity you agree to the [corporate contributor license
-agreement][corporate-agreement].
-
-[individual-agreement]: https://docs.gitlab.com/ee/legal/individual_contributor_license_agreement.html
-[corporate-agreement]: https://docs.gitlab.com/ee/legal/corporate_contributor_license_agreement.html
-
-
 ## Contribute to GitLab
 Thank you for your interest in contributing to GitLab. This guide details how

LICENSE

-The MIT License (MIT)
-Copyright (c) 2014-2017 GitLab B.V.
+Copyright (c) 2011-2017 GitLab B.V.
+With regard to the GitLab Software:
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
@@ -19,3 +19,7 @@ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 THE SOFTWARE.
+
+For all third party components incorporated into the GitLab Software, those
+components are licensed under the original license provided by the owner of the
+applicable component.