This introduces A new type (`Limit`), which allows Limits
and "Reservations" to have different options, as it's not
possible to make "Reservations" for some kind of limits.
The `GenericResources` have been removed from the new type;
the API did not handle specifying `GenericResources` as a
_Limit_ (only as _Reservations_), and this field would
therefore always be empty (omitted) in the `Limits` case.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>