Ad rack/dc avareness

[ernado]

1. Add rack and dc node labels to configuration
2. Create rack, dc in yt
3. Configure rack, dc in components

References:

yt create rack --attributes '{name=rack_name}'

"rack": "fake",
"tags": [..., "rack:fake", ...]

Probably this should be done via mutating admission webhook on pods, that gets node labels and sets it as environment variables or pod labels.