Add zone edit method

[beltofte]

Adding missing method for editing a zone.

• editZone()

[beltofte]

Okay. Stupid lint. Fails if a class has more than 10 methods. A bit hard to move e.g. the cache purge methods to a separate class without breaking all existing places where people use these methods. Does not really make sense from a logical perspective to move the new editZone() method to a separate class.