Mattermost releases under MIT license, AGPL does not apply

Mattermost releases (the standard compiled versions of source code released by the core team) will be available under an MIT license, rather than the Apache-AGPL license, starting with v1.0.

The change to MIT was requested by the GitLab community to make it easy to deploy Mattermost in organizations who prefer MIT. While we could have also offered a commercial license or Apache, MIT was specifically requested.

We anticipate over 99% of users will use the compiled releases, and the MIT license makes this straight forward.

See MIT-COMPILED-LICENSE file in Mattermost releases for details.

The purpose of AGPL in the Mattermost source code is to require modifications to the core product be shared with the community, rather than being kept proprietary. Since Mattermost releases are compiled binaries, the source code is not available for modification, therefore AGPL is unnecessary and hence removed. Regarding the less than 1% of users who want to modify the core product source code, AGPL still applies so that those changes can benefit 100% of the community.

Big thanks to the GitLab community for feedback on this change.