Added #permissions= as deprecated to maintain backward compatibility of Hydra::AdminPolicy with hydra-head < 6.4.
(In hydra-head < 6.4 Hydra::AdminPolicy included Hydra::ModelMixins::RightsMetadata, which provided #permissions=.)

Removed permissions= from Hydra::ModelMixins::RightsMetadata as it is now provided by included module Hydra::AccessControls::Permissions.
Merge pull request #109 from dchandekstark/deprecated-permissions-setter

Added #permissions= as deprecated to maintain backward compatibility of ...
Preparing for 6.4.0.rc4 release