Better support for Base URI

[vinibaggio]

If an application that uses Omniauth is mounted under a sub URI (such as passenger_base_uri /sub_uri; ), OmniAuth is unable to match either callback_path or request_path.

Also, when generating the callback_url, it should be considered.

[josevalim]

It is important to notice that when passenger_base_uri is used, the passenger_base_uri is added as "SCRIPT_NAME" to rack. The fact that today Omniauth considers the SCRIPT_NAME to match the URL is wrong because this means developers need to worry about where their website will be "mounted" in production to properly configure their path_prefix.

On the other hand, SCRIPT_NAME should always be used on generation, otherwise we may link to an URL outside that sub url.

Therefore, +1 for this pull request and fix. :D

[graywh]

Yes, this corrects the issues I've had, too.

[atd]

This also affects our project. Another +1 for this pull request

[mbleigh]

I had never actually looked at the SCRIPT_NAME part of Rack before...learn something new every day.

[graywh]

This is still an issue for callback_path. + script_name should be moved from callback_url to callback_path.