Improve `meteor update` output when at latest compatible version

[lorensr]

Migrated from: meteor/meteor#5270

$ meteor update
...
The following top-level dependencies were not updated to the very latest version available:
 * stevezhu:fbgraph 1.2.0 (2.0.0 is available)
...
To update one or more of these packages, pass their names to `meteor update`. 
$ meteor update stevezhu:fbgraph
The specified packages are at their latest compatible versions.

In this case, I don't think I have any other packages that depend on fbgraph < 2. I think it's just saying "latest compatible" because it's a major version number change. But in general, it would be helpful if both meteor update and meteor update X tell me:

1. X is latest compatible because of Y pkg (related: #4610) OR because different major version
2. In latter case, how can I update to new version

---

From David:

It's the meteor update command code: https://github.com/meteor/meteor/blob/devel/tools/cli/commands-packages.js#L1545

The meteor update command could definitely use some UX improvements. Anywhere Meteor says something is at the "latest compatible version" it basically just means it isn't necessarily at the latest version! Not a helpful message.

[StorytellerCZ]

Related to #390