modified update command: don't stop resolving when a package isn't found in registry

instead display a warning and continue with the rest of the packages. additionally update
now ignores all links before even trying to resolve them and displays a message instead.
display the link as it is, not the canonical path
use module id, not the path to rp.js

this ensures that the module ids are always relative (starting with "rp."), which affects logging
(log4j.category.rp = DEBUG)
log resolver errors