jones-ndb 7.6 cannot connect to NDB 8.x

[jdduncan]

When Jones is built with ndbclient from 7.6, attempts to connect to an 8.x cluster fail with an error from wait_until_ready

[jdduncan]

The actual error here is due to missing NDB version compatibility rules. When wait_until_ready() returns an error, jones-ndb should use getNdbError() which might hold additional information. (If it does not in this case, that would be an NDB bug).