Change routes for more pretty disks api
Remove handlers for working with disks from node.py file
Rename tests node attrs to node disks
Add disks handlers
Rewrite tests for disks
Add handlers for node volumes information
add skeleton for volumes information tests
Use a -= 3 instead of a = a - 3
Cleanup validators
Change json structure for release fixtures
Add type vg to fixtures
Add CannotFindVolumesInfoForRole exception
Refactor structure of volumes in fixtures
Take volumes metadata from fixtures for tests
fix fixture
Communications with UI in simple format
Add format convertor
Implement tests for volumes info
Fix defaults data generations
Fix disk size callculation for UI, reserve 210MB for mbr and boot partition