Fixes deprecation warning:
```
DEPRECATION WARNING: The success? predicate is deprecated and
will be removed in Rails 6.0.
Please use successful? as provided by Rack::Response::Helpers.
```
Update the help controller to correctly handle relative links on the help pages
when the relative link is before an external link on the same line in the
markdown file.
Test cases have been implement to check for
- relative links before external link on same line,
- HTTPS in query part of link,
- URLs without '//' and
- protocol-relative links.
Updates specs to use new rails5 format.
The old format:
`get :show, { some: params }, { some: headers }`
The new format:
`get :show, params: { some: params }, headers: { some: headers }`
An external link was recently added but was broken because
'https://gitlab.com/help/' was prepended to every link in the page.
Since no link in the main help readme begins with "help" and since doing
so wouldn't make sense, the substitution conditionaly prepending "help"
can be simplified and reused.
Signed-off-by: David Wagner <david@marvid.fr>
