Improvements to registry status outputs

[KristofferC]

Say you have an outdated General registry that is not in DEPOT_PATH[1]. The following then happens:

• You will install outdated packages
• registry status will show the general registry like everything is ok
• registry up will not update any registries (because not first in depot path).

Improvements would be:

• registry status shows the the registry is outdated (can be seen with Pkg.Registry.pkg_server_registry_info())
• registry up does a warning if a registry is outdated and not first in depot path

[fredrikekre]

Could perhaps also group by depot path to make it clear that lower depots are read only?