Handle block and ledger height mismatch

This 2020.04.01.0 release fixes a bug that results in hotspots getting stuck syncing. A gateway OUI field was also added to the blockchain protocol. The new gateway OUI field is a breaking change that requires a software upgrade.
A 2020.04.01.0 release was deployed to the beta group around 5:30 PM PST on Wednesday April 1st. If overnight testing goes well we will release 2020.04.01.0 to general availability the following morning.