Martin Lowe authored Jan 16, 2020 and Mikaël Barbero committed Jan 22, 2020

Updated SecretConfigSource to check JVM then env vars for secret
location. Removed calls in dockerfile to contain secrets, and instead
expect it to be mounted as a volume. Instructions in docker file has
been updated.

Signed-off-by: Martin Lowe <martin.lowe@eclipse-foundation.org>