Bug 11757: remove dependency on POE

The last use of the POE family of Perl modules went away with
the removal of zebraqueue_daemon.pl per bug 9001.  Consequently,
this patch removes POE as a dependency.

To test:

[1] Verify that "git grep POE" and "git grep libpoe" report
    nothing.
[2] Verify that koha_perl_deps.pl -a does not report POE
    as a dependency.
[3] (extra credit) verify that Debian packages can be built
    that do not list libpoe-perl as a dependency.

This patch also updates some distro-specific installation
instructions and scripts, but makes no representations about
whether those instructions currently work.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>
Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>