Incorrect redirect uri given to idp, if application is not the first element in the path

[tlanfer]

Steps to reproduce

• Create an application for the d.velop cloud using the dvelop-sdk-idp
• Deploy the application in such a way, that the endpoint uri is something like https://some.where.com/dev/appname
• Make sure you are NOT logged in
• Try opening a resource which requires an active idp session, e.g. /appname/idpdemo
• Log in as usual

Expected behaviour

• The SDK uses the request uri to generate a redirect uri to give to the d.ecs identityprovider
• After login, the user should be redirected back to the url /appname/idpdemo

Current behaviour

• The redirect url given to the d.ecs idp is /dev/appname/idpdemo
• The user ends up on a 404 page, because the app "dev" does not exist