short-circuit some uncompletables

Some, like "search" are simply too slow for dynamic completion.

Also: add options for completables (authorized, bundle, etc.)
reorder, add comments
alphabetize
simplify/standardize options lists
act on this command rather than previous completion

also: remove duplicate handling of `meteor create --example`
hardcode name of meteor executable

Reads better, and I didn't see much value in the abstraction.