client: Move local cache validation to "isr checkp"
client: Move local cache validation to "isr checkp"

- Move verification of keyring and local cache from "isr stat -c" (which
is unintuitive) to "isr checkp".  Move original functionality of "isr
checkp" (which is not usually useful) to "isr checkp -e" using new
-e/--remote command-line option.

- Make --checkstate option non-stacking, since that functionality was only
used to tell statparcel() what should be validated (in an undocumented way)

- Clean up isr_srun("checkparcel") flag handling in checkparcel()

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