Add --auto-add-exclude-directories option

Currently FPM ignores directories only from filesystem package, this
convers a lot of directories that cannot be owned by user packages, but
not all.  This option allows to add additional directories that should
be ignored (e.g. /etc/init.d/, /etc/sysconfig/).
Merge pull request #640 from vrutsky/rpm_auto_add_exclude_list

Add --rpm-auto-add-exclude-directories option