Svalinn fails to connect to new database nodes when upgrading the database

[kristinapathak]

When the database switches to new database nodes, certain svalinns have intermittent database failures because they fail to connect to the database. A restart fixes this issue.

[kristinapathak]

When there's no host in the list, it needs to restart a connection in the cluster.

[kcajmagic]

The log file from svalinn produced gocql: no hosts available in the pool