Make wmiistatus run all the time and wait for wmii_path to exist

Make wmiistatus run all the time and wait for wmii_path to exist

Instead of exiting as a file inside wmii_path cannot be opened, we wait
until wmii_path is found again (particularly the /rbar part, that is),
re-setup our files and continue as if nothing happened.

This will make wmiistatus survive restarts of wmii and make it wait for
/mnt/wmii to appear when booting up (and wmiistatus gets started before
wmii itself)