conf/completion: Respect --server/--user when completing local parcels
conf/completion: Respect --server/--user when completing local parcels

- Rename _isr_checked_out() to _isr_local_parcel()

- Replace _isr_parcel_keys() with a new _isr_checked_out() function which
walks the available parcel.cfg files and generates a list of
UUID/server/user/name tuples.  Update callers of _isr_parcel_keys() to
filter this list for the information they want.

- Update _isr_local_parcel() to return only parcels matching the current
server and userid

- Remove obsolete comment

cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr