facts.py

The list of modules and roles is needed in several scripts now,
therefore it makes sense to have one place for this.

Here are the current variables:

BASE_DIR:           Base directory of the repo
ROLES:              List of roles in the roles folder
MANAGEMENT_MODULES: List of management modules in the plugins/modules
                    folder
ROLES_MODULES:      List of modules in the roles/*/library folders
ALL_MODULES:        List of all modules, the management and the roles
                    modules

All lists are sorted.