[UX] No Save button on fabric/vlan/subnets

[Jill Rouleau]

There is no Save function on fabric/vlan/subnets pages - changes are written to the database as they are typed. By autocommiting configuration changes it is very easy to imagine a scenario where one admin is starting to input a change then gets distracted halfway through, or is just slow to input data, or even has accidentally clicked/typed into a field without realizing, and another admin finds themselves deploying with half-cooked config.

Config changes should have an edit,save workflow to ensure changes are complete before being committed.

MAAS 2.1.3+bzr5573-0ubuntu1 (16.04.1)