[ranger-kms] KUDU-3385 - part2: mini_ranger init

For Kudu to be able to provide data at rest encryption, a separate key
management service can be used for encrypting/decrypting keys.

This patch lays the groundwork for integrating RangerKMS as such a
service, enabling us to create mini test clusters with it, thus making
it possible to test the required interactions properly.

Two existing services mini_ranger and mini_pg were modified, so that the
mini_pg instance could be shared between mini_ranger and mini_ranger_kms
and other future services as well.

Change-Id: I11617468245068dd732fb3f2578bb086b2f6024f
Reviewed-on: http://gerrit.cloudera.org:8080/18645
Reviewed-by: Alexey Serbin <alexey@apache.org>
Reviewed-by: Attila Bukor <abukor@apache.org>
Tested-by: Kudu Jenkins
16 files changed