Release 5.0.0 - Juno

Changes in this release:
* Added heat::policy to control policy.json
* Deprecated the sql_connection parameter for database_connection parameter
* Adds parameters to configure deferred authentication method in heat::engine in accordance with new Juno defaults
* Bumped stdlib dependency to >=4.0.0
* Added parameters to control whether to configure users
* Added manage_service parameters to various classes to control whether the service was managed, as well as added enabled parameters where not already present
* Added the ability to override the keystone service name in keystone::auth
* Migrated the heat::db::mysql class to use openstacklib::db::mysql and deprecated the mysql_module parameter

Change-Id: I1eb3c5f278c1ff348fca3173c979cab2945e7a54
Merge "Release 5.0.0 - Juno"