Minor updates to widearea usage page, including some planetlab specific notes. Also convert examples to use physical nodes in tb-fix-node, and fix the types using in tb-set-hardware statements.
Minor updates to widearea usage page, including some planetlab
specific notes. Also convert examples to use physical nodes in
tb-fix-node, and fix the types using in tb-set-hardware statements.

nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome