Can't log in to last.fm; token login not even attempted

[kermitfrog]

This might be related to #203 and #174.

I set up the config (api-key & secret inclusive) and tried to log in to last.fm.
Then it asks for a username and password.
When given these, it still fails with the output

Failed to authenticate with Last.fm

Caused by:
    Authentication failed: Status code 403 Forbidden indicates failure
Warning: no scrobbling services defined

I briefly ran it in a debugger and from what I can tell:

• api-key & secret are correctly read from the config, but never used
• instead it looks for a session key (that can't be there before a succesful login, right?)
• that fails and it asks for username and password instead
• that also fails for unknown reason, so it ends up with no scrobbler configured