Activate cashaddr on Jan, 14

Summary: This activate cashaddr by default on Jan, 14. The flag -usecashaddr can still be used to select manually which format is desired.

Test Plan: Run bitcoin-qt and check usecashaddr is disabled by default.

Reviewers: dagurval, schancel, Mengerian, #bitcoin_abc

Reviewed By: schancel, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D840