Add `Gitlab.com?` method

To be used as a feature flag for GitLab.com-only features, such as
welcome emails.

We will be careful to only use this to disable features or functionality
that do not make sense for any installations that aren't GitLab.com. We
will not use this to restrict features from other installations or keep
them "exclusive" to GitLab.com.

See merge request !3682

API: Return 404 if user does not have access to group

Closes #15185 

After !3587 is merged, I'll update this one to also fix the return code of the tests in !3587.

See merge request !3683

API: Ability to move an issue

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/14741

See merge request !3593

improve formatting



See merge request !3688

Added ability to add custom tags to transactions

cc @pcarranza 

See merge request !3674

Adjust the default trusted_proxies to only include localhost

And also allow other trusted proxies to be added from the config.yml.

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/3538

Omnibus config: https://gitlab.com/gitlab-org/omnibus-gitlab/issues/1208

See merge request !3524

Tie example config to JIRA screenshot

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/15203

See merge request !3693

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/15203

One use case for this is manually setting the "action" tag for Grape API
calls. Due to Grape running blocks there are no human readable method
names that can be used for the "action" tag, thus we have to set these
manually on a case by case basis.

Allow to close invalid merge request

fixes #15044

See merge request !3664

Docs for the new branch button

[ci-skip]

Closes #3886 

@axil Could you check this and make sure this is up to your standards?



See merge request !3425

Fix repository cache invalidation issue when project is recreated with an empty repo

See merge request !3692

[ci skip]

API: Ability to update a group

This makes it much easier to update a group after introducing the group visibility.

* Closes #14991 

See merge request !3587

To reproduce:

1. Create a project with some content
2. Rename the project
3. Create a new project with the same name.
4. Boom - 404.

After step 2, the branch and tag counts were not being cleared. This would
cause `repository.has_visible_content?` to erroneously return `true`
for the newly-created project.

Closes #13384

Wrap text in notes box if longer than code in diff

* Fixes branch name overflow
* Text and inline `code` wraps in comments
* `code` blocks scroll horizontally

![Screen_Shot_2016-04-11_at_4.59.15_PM](/uploads/39eee7d35ea79d1a3944aa6281b72121/Screen_Shot_2016-04-11_at_4.59.15_PM.png)

See merge request !3626

Fix todo_target_path for todos where target was removed

Fixes #15187 

See merge request !3684

To be used as a feature flag for GitLab.com-only features, such as
welcome emails.

We will be careful to only use this to disable features or functionality
that do not make sense for any installations that aren't GitLab.com. We
will not use this to restrict features from other installations or keep
them "exclusive" to GitLab.com.