Only allow group/project members to mention `@all`

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/3473

See merge request !2205

Fix typo on triggers docs



See merge request !2214

Remove incomplete text on triggers doc



See merge request !2213

open and close issue via ajax request. With tests

Close and Reopen issues with ajax request.

See merge request !2164

Revert vote buttons back to issue and MR pages

https://gitlab.com/gitlab-org/gitlab-ce/issues/3672



/cc @dzaporozhets @JobV 


![joxi_screenshot_1450809309400](/uploads/379a75505e0d5f24e743aa0a6a6684e2/joxi_screenshot_1450809309400.png)


See merge request !2206

Add Open Graph meta tags



See merge request !2192

Adding  CRIME Vulnerability to Security doc

Added an additional page to the security section that goes over current status and fixes for the TLS Protocol CRIME Vulnerability. Also added its respective link at the security README. 

Any suggestions appreciated @JobV @sytses 

See merge request !2102

Documentation on CI triggers

Closes #3432

## Notes

* Implement build trigger API - https://gitlab.com/gitlab-org/gitlab-ci/merge_requests/229
* Build trigger API - https://gitlab.com/gitlab-org/gitlab-ci/issues/257
* Build pipeline - https://dev.gitlab.org/gitlab/gitlab-ci/issues/282 and https://gitlab.com/gitlab-org/gitlab-ce/issues/3743
* Dependent builds - https://dev.gitlab.org/gitlab/gitlab-ci/issues/328
* Travis docs - https://docs.travis-ci.com/user/triggering-builds/
* Custom variables Circle CI example - https://circleci.com/docs/nightly-builds
* Triggers API (CI) will be done in a separate MR
* Notify https://gitlab.com/gitlab-org/gitlab-ci/issues/368 once done

## Docs needed to change

- [x] `doc/ci/README.md`
- [x] `doc/README.md`

See merge request !2161

Add API support for looking up a user by username

Needed to support Huboard

See merge request !2089

Require two factor authentication

Allow Admins to force 2FA on their users, as discussed here: gitlab-org/gitlab-ce#3783

See merge request !2155

Escape all the things.

See merge request !2209

simplified code and fixed stuffs

Enable "Add key" button when user fills in a proper key

Closes #4295

See merge request !2208