Pull master

Adds a rake task which can be used for removing EXIF
data from existing uploads.

Also note that apps will be released into the Kubernetes namespace for
the environment, and that GitLab < 11.4 used a dedicated Tiller

Domain was introduced on 11.8 and was not included on the
Project Cluster API. With this change user will be able to include
domain when adding and updating a cluster. Domain will also be included
on the GET calls.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/59441

We also enable the rubocop that makes it mandatory

When validating parsing, copy pasting should just work, but
instead we created 

Update lfs_administration.md to add documentation on Rackspace Cloud Files for LFS object storage, including a note on Fog requiring the temp-url key even when the object container is public ("CDN enabled" in Rackspace terms)

Signed-off-by: NRémy Coutable <remy@rymai.me>

Since external diffs are likely to be a bit slower than in-database
ones, add a mode that makes diffs external after they've been obsoleted
by events. This should strike a balance between performance and disk
space.

A background cron drives the majority of migrations, since diffs become
outdated through user actions.

The new version requires `python3` to be available. In omnibus
installation this is already a reality as we are currently pathing
previous `gitlab-markup` version to use `python3` instead of `python2`.

We are now requiring `python3` with the gem without having to patch it.

As a consequence to also make it easy to use it in development, we've
introduced a `Pipfile` and `Pipfile.lock`, working similarly to
`Gemfile` and `Gemfile.lock`, and added documentation on how to use
them.

Adds the groundwork needed in order to persist multi-line suggestions,
while providing the parsing strategy which will be reused for the
**Preview** as well.

This makes it easier to debug Gitaly performance issues in the field.

This commit also makes the tracking of query time thread-safe via
RequestStore.