Added command line installer argument "allmodules" to enable code path for installing all modules located on disk

**NOTE** For some reason the PR here did not merge anything, probably because we renamed a branch at some time (sorry). The original PR is here: https://github.com/PrestaShop/PrestaShop/pull/2011

There was an unused but useful code path for installing all the modules located on disk instead of just the white-listed modules that come with Prestashop. This is useful when automating many installations with a set of modules other than the core modules.

I broke the method up into two methods, one for getting the modules on the disk and another for using the white-list.

This change does not change the default behavior of Pretashop in any way.

When running the command line installer:

php install_cli.php --allmodules --domain=foo.com --db_name=me --db_password=secret ...