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
would be better to move the strings to some constants file and use variables everywhere, so that if we ever change the name of a setting we just have to change it in one place.