Release 5.0.0 - Juno

Changes in this release:
* Added class to manage policy.json
* Changed the default value of the san_thin_provision parameter for eqlx
* Added database tuning parameters
* Made keystone user creation optional when creating a service
* Added ability to hide secrets from logs
* Added parameters for netapp and and cinder-api workers
* Corrected the package name for cinder backup
* Added support for the EMC VNX direct driver
* Migrated the mysql backend to use openstacklib::db::mysql
* Added support for availability zone

Change-Id: I08b059778354b9c2280501d8defa2e4884b8f3a7