The two json files in this diff were generated via:
```
scripts/get_merkle_root 822000 --json-output electrumabc/checkpoint.json
scripts/get_merkle_root 1477500 --json-output electrumabc/checkpoint_testnet.json --server telectrum.bitcoinabc.org:60002:s
```
Run the software, check that we are connected, that the servers are not blacklisted (would happen if the merkle root was wrong).
Build some release binaries and test them, to make sure the new data files are properly packaged.