Authenticate or create users from OAuth providers

Create satellites during update to 6.0. Fix #4938

add missing comma(s) in api examples

have email views use iid

Satellites for projects that were located in the root namespace needs to be recreated once they've been migrated to the creator’s namespace during the upgrade process.

This can be achieved by running the sudo -u git -H bundle exec rake gitlab:satellites:create RAILS_ENV=production during the update process.

The command has been added to the 5.4 to 6.0 update doc.

Dont update namespace if User name was changed. Use user#username for namespace name because Namespace#name validates by uniq

Standardize recently added commit diff api url

Fixed up wording on the new SSH key page.

update gitlab:check to look for update hook, not post-receive

Use "/commits/:sha/diff" as opposed to "/commit/:sha", keeping in line
with existing api urls (e.g. "/projects/:id", etc.)

Fix 500 error resulting from a diff api call with an invalid commit hash

Move "/commits/:sha/blob" to "/blobs/:sha", leaving the old path for
backwards compatibility.

Add ability to get a single commit via "/commits/:sha"

Show permissions for all project.
Add ability to remove user from group if not an owner
Remove unnecessary admin controller

Provide UI with explanation what happens when you block or remove user
When remove user - remove all groups where user is an only owner