Oxygen: the sf plugin should not work in a production org without explicitely accept the terms

Example we run the command:
```
$ sf check object --sobject Account --target-org MyProductionOrg --json
```

That command should raise an error because terms are not accepted in production org.


Two things:
- Make sure this command throws an error
- Implement an optional new flag "--accept-terms" (type boolean) to accept the terms explicitely