0.15.0

Features:

• Node-sessions are now stored by DevEUI. Before the node-sessions were stored
  by DevAddr. In case a single DevAddr is used by multiple nodes, the
  NwkSKey is used for retrieving the corresponding node-session.

Note: Data will be automatically migrated into the new format. As this process
is not reversible it is recommended to make a backup of the Redis database before
upgrading.