bacula: Also encrypt the data channel

The actual data is already encrypted by the client before being
transmitted on the network but the metadata (filenames, permissions etc)
was not. This will incur some extra load on both servers due to the
extra layer of encryption but it should be relatively neglegible

Change-Id: I499a0d50d54e7b8e7d67f130d8887ee96d09c76d
Merge "bacula: Also encrypt the data channel" into production