Copy PHP extensions INI files to the cartridge code for maintainability

- PHP 5.3: Copy RHEL /etc/php.d/*.ini files
- PHP 5.4: Copy RHEL /opt/rh/php54/root/etc/php.d/*.ini files
- PHP 5.5: Copy f19 /etc/php.d/*.ini files

Motivation:
- We want to be able to enable/disable PHP extensions in gears
- We want to be able to edit PHP extensions settings in gears
- We want consistency for all the INI files across all nodes.
  Currently, the INI files are marked %config(noreplace) in RPMs
  and may theoretically differ from node to node.

Set PHP_INI_SCAN_DIR env var to scan customized extension INI files

- Scan ${OPENSHIFT_PHP_DIR}configuration/etc/php.d/ directory
  instead of the default system's scan dir (eg. /etc/php.d/)