Targets list customization improvements.

Setup an easy way to customize targets list to deploy, simply in a
specifi file.
Moved customizations logic in library.
Added some Kali customizations.

Customizations:

- packages
Allow user to set a package list to install in Kali linux

- synced_folders
Allow user to set a list of directories to sync in Kali linux.
Added custom scripts execution.

Customization to allow user to puts some scripts into custom/scripts/ to
be executed on deployed Kali linux.
Added 0.3 in ChangeLog

This version added customizations feature.