Fortnox sandbox for integration tests

[ehannes]

It would be nice if Fortnox would sponsor us with a free Sandbox account to run our integration tests agains. (The current one we are using should be replaced).

It would be even better to be able to run tests against a real database which can be emptied between test runs.

We should probably filter our API credentials as well. We could have real ones credentials in .env. Then we could create a rake task for replacing our real credentials in our VCR cassettes to use mocked ones declared in .env.test.