Make Evergreen Perl modules installable via Module::Build to match OpenSRF

Make Evergreen Perl modules installable via Module::Build to match OpenSRF

Build.PL gives us an install-time check on dependencies; right now
the required versions are not set, but we can update these easily
to start catching some of the problematic modules that have tripped
sites up in the past.

Build.PL really seems to want a top-level "OpenILS.pm" so add a placeholder
accordingly.

Adjust references to /src/perlmods/ to /src/perlmods/lib/ even though
a number of the affected scripts are probably cruft.

Use autoconf to provide the default paths in O:WWW:Web and O:WWW:Method;
next step is probably to teach autoconf to ask Build.PL to do that for
us to make the OpenILS Perl modules more independent.

git-svn-id: svn://svn.open-ils.org/ILS/trunk@19340 dcc99617-32d9-48b4-a31d-7c20da2025e4