v1 -> v2

The referral structure is automatically transferred from the previous version (Cadabra 1.0), building a binary structure. The binary tree is constructed based on the date and time of the existing referrals' registration on Cadabra 1.0 platform.

Referral ranks require less number of ABRA tokens. Also the ranks cost maybe decided in DAO voting if ABRA price changed and ranks cost too expensive or too cheap.