Autoprovisioner implementation

[isbm]

Implements automatic provisioner. User merely says what host to add, the rest is automatic, in case there is no packages for the target OS (typically not, this is embedded!).

This PR adds the following features:

1. Adding hosts
2. Removing hosts
3. Upgrading remote minion components
4. Hopstart: a network replacement for init system, in case target host is read-only and reboot doesn't restart the minion anymore.
5. Host detection and more traits

• Implementation
• Tests
• Integration tests
• Documentation
• Examples