Due to the NGINX rewrite appending a "/" on URLs, the post-login
URIs are also given a trailing slash in. This made them invalid.
Now, clients generated with the init-db command are given
post-logout-redirects for both with and without a trailing slash.
Thus redirect after login works correctly now, and doesn't
bring you to steering-login (but to dashboard).

Fixes meta#94

- `Category`,
- `FundingCategory`,
- `Language`,
- `MusicFocus`,
- `Topic`,
- `Type`

- `Category`,
- `FundingCategory`,
- `MusicFocus`

Feat: Generate visual data model

See merge request !23

refactor schedule REST API

Closes #101

See merge request !22

The conflict responses should be send with an HTTP 409 status code as
they’re defined in our documentation. This was not the case as the
dashboard couldn’t handle these error codes, but is now fixed in
dashboard@4a07ad9e.

Until now the steering API client was expected to submit two requests.

1. The initial schedule request, with a `schedule` object
2. A second schedule request, with an additional `solutions` object

This `solutions` object was empty, if no conflicts arose from the
submitted schedule in the first place. But instead of just creating the
requested schedule if no conflicts were detected we still required that
second round-trip, introducing possible race conditions in the client,
if another successful scheduling request was made between requests.

From now on the steering API will create schedules if no conflicts have
been detected and will only require the client to submit solutions if
there really are conflicts to solve.