Destination parameter not respected

Problem/Motivation

When you enter a destination in the login link, it takes you to the destination directly instead of first logging you in.

Steps to reproduce

1. Add a link /user/login/strava?destination=/node/1
2. It takes you to the page without logging in.

Proposed resolution

Add a check if a destination has been set, unset it and readd it as a destination after the authentication.

Remaining tasks

review patch