Enchance configuration

[zverok]

1. It should be possible to configure executable with reality --config reality.yml
2. Consider using "current folder" trick like other tools, e.g. if reality binary run in folder containing .reality.yml -- the latter should be used.
3. Reality.check! should say which services are configured, which are not and for what purposes they serve. Also note "demo-configured services"
4. Better documentation for configuration process.