Bug 11155: remove old PostgreSQL schema and MARC framework scripts

Bug 11155: remove old PostgreSQL schema and MARC framework scripts

This patch removes the legacy Pg schema and MARC framework scripts
as they're out of date.  They will be replaced by use of DBIx::Class
to deploy the schema.  Loading the sample data and settings will be
accomplished either by making the current scripts in installer/data/mysql
DBMS-independent (or, at least, able to be processed by both MySQL and Pg),
converting them to flat text files and writing code to load them, or a
combination of the two approaches.

To test:

[1] Verify that installer/data/Pg is removed.  There is some code
    in C4::Installer that refers to that directory, but it cannot
    be reached through normal means.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>
Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>
(cherry picked from commit 458ef35a6a5c7da5523e8c1c208fdf3fee5ae4b6)
Signed-off-by: Fridolin SOMERS <fridolin.somers@biblibre.com>