Update CONTRIBUTING.md and LICENSE to reflect DCO

See https://gitlab.com/gitlab-com/organization/issues/146

[ci skip]

CONTRIBUTING.md

@@ -4,13 +4,18 @@ Thank you for your interest in contributing to this GitLab project! We welcome
 all contributions. By participating in this project, you agree to abide by the
 [code of conduct](#code-of-conduct).
 
-## Contributor license agreement
+## Developer Certificate of Origin + License
 
-By submitting code as an individual you agree to the [individual contributor
-license agreement][individual-agreement].
+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.
 
-By submitting code as an entity you agree to the [corporate contributor license
-agreement][corporate-agreement].
+[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._
 
 ## Code of conduct
 

LICENSE

-The MIT License
+Copyright (c) 2015-2017 GitLab B.V.
 
-Copyright (c) 2015-2017 GitLab, Inc.
+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.