Allow --overrides for enclosed build tasks

[jessehouwing]

When an extension packages one or more build tasks it would be nice if we'd be able to override properties of the build tasks upon packaging.

At the moment I'm using a Token Search & Replace script prior to packaging instead.

I'd love to be able to override:

• Version of the task

And ensure it is in line with the extension. Or simply not having to specify a version at all, and have the extension version be leading.