Fixes to Makefile.am and install.pl.in

make test shouldn't require the eprints user
Added missing README.pod to distribution (debian)
Added missing DESTDIR to install-data-hook
Make directories for installing files into
DESTDIR ought to be additive
Use make_path to create parent directories too
File::Path::make_path
make dist without prefix
Use $ENV{PREFIX} in install.pl
Fixed install.pl installing with PREFIX under make dist
Merge branch '3.3' of github.com:eprints/eprints into 3.3