Upgrade script should check for compatible framework updates

[tomgreenfield]

Expected Behaviour

The automatic upgrade functionality should check for updates in the currently installed framework's major range, e.g. instances running 3.4.0 should upgrade to 3.5.3 and instances running 4.0.0 should upgrade to 4.1.1.

Actual Behaviour

The update check for the framework is restricted to the version specified in package.json's framework field.

Steps to Reproduce

1. Run node upgrade and press ↵ Enter on both prompts.

[taylortom]

Think this is more of an enhancement than a bug, as the code should be limiting the app based on the value in package.json (which is 2).

We've got two scenarios to cover here:

1. New installs: which version is pulled down.
2. Upgraded installs: what range should be used.

I'd prefer not to update package.json each upgrade, as this will likely lead to confusion; moving over to use a config.json value probably makes more sense.

[tomgreenfield]

If the major range for an upgrade was determined from the currently installed framework then I'd have fewer gripes now bumping to 4 for new installs.

Agree with using the config JSON; I'm not a fan of the stagnant frameworkRevision field that gets left behind in there at present.