client side code. Two new files, to be included by any client side
script, which define all the paths. For /bin/sh scripts:

	. /etc/emulab/paths.sh

and for perl scripts:

	BEGIN { require "/etc/emulab/paths.pm"; import emulabpaths; }

Each defines a number of variables: ETCDIR, BINDIR, VARDIR, BOOTDIR,
LOGDIR, and LOCKDIR. They also set the path properly for the script.

This gets rid of the different hardwired paths, and reduces it to just
one for everyone.