This adds support for the optional blueprint section [customizations].
Use it like this:
[customizations]
hostname = yourhostnamehere
[[customizations.sshkey]]
user = root
key = root user key
- Fix `projects_depsolve()` to not consider a successful empty response
(rc == 0) as an error.
- Fix recipe_from_dict() to default modules and packages to empty lists
instead of `None`, to avoid a Python-ism in the API for consumers and
stay compatible to the bdcs API.
Fixes#290
