v1.0.0

Backward-incompatible change from 0.13.0 - Ezid::Metadata.register_element has been removed. Custom elements can be accessed on Ezid::Identifier instances by keys:

>> i = Ezid::Identifier.new
=> #<Ezid::Identifier id="" status="" target="" created="">
>> i["foo"] = "bar"
=> "bar"
>> i["foo"]
=> "bar"
>> i.metadata
=> {"foo"=>"bar"}