Port version 1.6 of the management schema upstream.

EAP will be introducing version 1.6 of the management schema, this needs porting upstream.

At the same point the coding convention we have adopted has been based around a linear progression of the configuration schemas, when version 1.5 was ported this still worked as 1.5 contained a subset of the changes that went into 2.0.

1.6 is going to be a special case as it will build on 1.5 so is already a subset of 2.0 but will also only contain a subset of changes that go into 3.0 - the risk however is our switch statements are built around dropping into a default block that is hit for all schema versions not explicitly listed.