Hierarchical Reservation

[Michael Park]

This is the design doc for hierarchical reservation:
https://docs.google.com/document/d/1Di6drHrBs3FWYJXKQjCTqQMi2Pfdt
Crf4OcuP3RZqmk/edit?usp=sharing.

Please take a look and provide feedback!

Thanks,

MPark