If a search turned up an issue, under certain conditions you would see this error:

```
ActionView::Template::Error (undefined method `path_with_namespace' for nil:NilClass):
     6:   - if issue.description.present?
     7:     .description.term
     8:       = preserve do
     9:         = search_md_sanitize(markdown(issue.description))
    10:   %span.light
    11:     #{issue.project.name_with_namespace}
    12:   - if issue.closed?
  lib/gitlab/markdown/upload_link_filter.rb:36:in `build_url'
  lib/gitlab/markdown/upload_link_filter.rb:31:in `process_link_attr'
  lib/gitlab/markdown/upload_link_filter.rb:18:in `block in call'
  lib/gitlab/markdown/upload_link_filter.rb:17:in `call'
  lib/gitlab/markdown.rb:127:in `gfm'
  lib/gitlab/markdown.rb:24:in `render'
  app/helpers/gitlab_markdown_helper.rb:61:in `markdown'
  app/views/search/results/_issue.html.haml:9:in `block in _app_views_search_results__issue_html_haml__4127460390996300432_59973760'
  app/views/search/results/_issue.html.haml:8:in `_app_views_search_results__issue_html_haml__4127460390996300432_59973760'
  app/views/search/_results.html.haml:20:in `_app_views_search__results_html_haml__589475855773452465_61761440'
  app/views/search/show.html.haml:5:in `_app_views_search_show_html_haml___1852335078065998536_69780120'
```

This standardizes all the project API formats. Also needed to support Huboard.

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

[ci skip]

https://github.com/kickstarter/rack-attack/releases/tag/v4.3.1

Fixes #4112

[ci skip]

Because Haml automatically indents the HTML source code, the contents
of whitespace-sensitive tags like pre and textarea can get screwed up.

[ci skip]

Closes #3649

[ci skip]

This is needed to support Huboard and a generally useful value.

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

[ci skip]

Also fixes an incorrect redirect after login with relative URL root:

Closes https://github.com/gitlabhq/gitlabhq/issues/8228

Closes #2750

Skipped CI because it has already passed. Had to rebase due to CHANGELOG.

Closes #3701

[ci skip]

Prevents an Error 500 when project fails to create due to invalid parameters.

See #3937

[ci skip]