Implement generating appups also with existing old releases from release store.

This is faster then generating appups with old git revisions / tags and can
be useful if also the erts version changed between the releases.
Implement generating upgrades also with existing old releases from release store.

This is faster then generating upgrade with old git revisions / tags and can
be useful if also the erts version changed between the releases.
Rename install strategies to deploy strategies.