Merge branches 'feature/project-export-ui-experimental' and 'feature/project-import' of gitlab.com:gitlab-org/gitlab-ce into feature/project-export-ui-experimental

Merge branch 'feature/project-export' of gitlab.com:gitlab-org/gitlab-ce into feature/project-import

Merge branch 'feature/project-import' of gitlab.com:gitlab-org/gitlab-ce into feature/project-export-ui-experimental

# Conflicts:
#	app/controllers/import/gitlab_project_controller.rb

Merge branches 'feature/project-export' and 'feature/project-import' of gitlab.com:gitlab-org/gitlab-ce into feature/project-import

Merge branch 'feature/project-export' of gitlab.com:gitlab-org/gitlab-ce into feature/project-import

# Conflicts:
#	lib/gitlab/import_export/command_line_util.rb

Merge branches 'feature/project-export' and 'master' of gitlab.com:gitlab-org/gitlab-ce into feature/project-export

[ci skip]

Support e-mail notifications for comments on project snippets

While working with project snippets recently, I noticed that notifications would not be sent out for comments on notes. This MR fixes this.

Note: I'm not completely sure why `ProjectSnippets#participants` returns an empty array if you don't include the concern that is already in `Snippets` but didn't dig into it any more.

Closes #2334

See merge request !3987

Closes #2334

Fix error when trying to create a wiki page

Closes #15527, #15569, #15623, #15630, #15637, #15653, #15870, #16558, #16875, #16987, #17016, https://github.com/gitlabhq/gitlabhq/issues/10317.

See merge request !3924

Fix "remember me" sign in option

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/4006

Prior to this change, 'remember me' was effectively always on because
the `_gitlab_session` cookie was always made persistent. With this
change it becomes possible again to have `_gitlab_session`be a session
cookie when 'remember me' is unchecked.

See merge request !4004

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

Remove duplicate entry in the CHANGELOG

[ci skip]

See merge request !4002

Backported minimal safewebhook implementation to GitLab CE

This brings a minimal implementation for gitlab-org/gitlab-ce#13478
backported from EE (gitlab-org/gitlab-ee!334).

Also added UI to configure Secret Token

Fixes #15365.

See merge request !3940

Codestyle changes to easy EE merge

Fix the GitHub Omniauth instructions

Technically the screenshot is also out of date, but I honestly don't care enough to go through the effort of making a sample application, taking a screenshot, etc.

See merge request !3976

Handle issue move access instead of raising error

Closes #15533

See merge request !3990

Closes #15533

Add more parameters to the filter_parameters config.

Adds Sentry DSN, Webhooks, Deploy Keys, etc.

Alphabetized the parameters and included line breaks between each parameter. Easier to merge into EE if there are any differences.

This also seems to be the more popular syntax for adding new parameters, from what I can find.

In the future we may want to [increase the specificity of some of these](http://blog.bigbinary.com/2016/03/07/parameter-filtering-enhacement-rails-5.html) once Rails 5 is out. e.g. instead of `:hook`, `"hook.url"` would be just as effective without removing potentially useful information from the logs.

cc: @stanhu 

See merge request !3971

Adds Sentry DSN, Webhooks, Deploy Keys, etc.

Alphabetized the parameters and included line breaks between each parameter. Easier to merge into EE if there are any differences.

This also seems to be the more popular syntax for adding new parameters, from what I can find.

Cleaned up/tweaked Project#open_branches

See commit c825404572040a3a45cb9e2b3d3e7d64900f66c9 for the details of the changes and https://gitlab.com/gitlab-org/gitlab-ce/issues/14280#note_4973648 for more information.

See merge request !3985