Feature/provisioner configfile

- [x] provisioner reads properties from a default config file, and optionally, an additional override file given with the ``-C <file>`` option
- [x] additional configs such as log rotation settings
- [x] removed all command line arguments except ``-C <configfile>`` and ``--register``
- [ ] we may consider changing config files to .rb... xml was just easy to implement first.
- [x] minor unrelated change: abort startup if unhandled exceptions in heartbeat thread