Our friends at GitHub show the programming languages for a long time,
and inspired by that this commit means to create about the same
functionality.

Language detection is done through Linguist, as before, where the
difference is that we cache the result in the database. Also, Gitaly can
incrementaly scan a repository. This is done through a shell out, which
creates overhead of about 3s each run. For now this won't be improved.

Scans are triggered by pushed to the default branch, usually `master`.
However, one exception to this rule the charts page. If we're requesting
this expensive data anyway, we just cache it in the database.

Edge cases where there is no repository, or its empty are caught in the
Repository model. This makes use of Redis caching, which is probably
already loaded.

The added model is called RepositoryLanguage, which will make it harder
if/when GitLab supports multiple repositories per project. However, for
now I think this shouldn't be a concern. Also, Language could be
confused with the i18n languages and felt like the current name was
suiteable too.

Design of the Project#Show page is done with help from @dimitrieh. This
change is not visible to the end user unless detections are done.

Fix bug setting http headers in Files API

See merge request gitlab-org/gitlab-ce!20938

Merge branch '49499-list-of-projects-not-loading-when-trying-to-create-an-issue-from-a-board-typeerror' into 'master'

Resolve "List of projects not loading when trying to create an issue from a board (TypeError)"

Closes #49499

See merge request gitlab-org/gitlab-ce!20955

Port of EE-translations

See merge request gitlab-org/gitlab-ce!20960

Allow users to set a status

Closes #35463

See merge request gitlab-org/gitlab-ce!20614

Resolve "Making instance-wide data tools more accessible"

Closes #41416 and #48507

See merge request gitlab-org/gitlab-ce!20874

New Crowdin translations

See merge request gitlab-org/gitlab-ee!6706

Remove fixes for MR refactor regressions from master

See merge request gitlab-org/gitlab-ce!20920

correct error message on helm tiller installation timeout

See merge request gitlab-org/gitlab-ce!20683

Add `runner_unsupported` CI failure

See merge request gitlab-org/gitlab-ce!20664

This reverts commit 740ae2d1, reversing
changes made to 1ba47de5.

This reverts commit 6c6988cb, reversing
changes made to 0d488c7b.

This reverts commit 5ba542b1, reversing
changes made to 32c831ea.

This reverts commit ced005f3, reversing
changes made to 9b01b293.

This reverts commit 2411ecb5, reversing
changes made to 58a0df7e.

This reverts commit 9c121352, reversing
changes made to c1b335e0.

Create update guide from 11.1 to 11.2

See merge request gitlab-org/gitlab-ce!20945

update installation docs branches for source installations

See merge request gitlab-org/gitlab-ce!20944

Support multiple scopes when authing container registry scopes

Closes #48968

See merge request gitlab-org/gitlab-ce!20617

Add support for ssh certificates (internal API)

Closes #34572

See merge request gitlab-org/gitlab-ce!19911

Update test-and-deploy-python-application-to-heroku.md

See merge request gitlab-org/gitlab-ce!20921

Rails5: fix flaky spec

See merge request gitlab-org/gitlab-ce!20953

Resolve "Allow issue's Internal ID (`iid`) to be set when creating via the API"

Closes #1756

See merge request gitlab-org/gitlab-ce!20626