Fix API authentication returns 400 when providing the wrong credentials

Simcha van Collem
2019-12-04T19:31:08+01:00

Closes #959

#### Previous behaviour
Steps to reproduce:

1. Authenticate at `/api/v1/token-auth`
2. Get a 400

#### New behaviour
Steps to validate that it works:

1. Authenticate at `/api/v1/token-auth`
2. Get a 401