Merge branch 'release-0.9.1' into develop
Added public methods `Ezid::Identifier#unavailable!` and `Ezid::Identifier#public!`
to effect status changes (addresses #2).
`Ezid::Identifier#unavailable?` accounts for possible reason (fixes #16).
Added public method `Ezid::Identifier#deletable?`.
Merge pull request #29 from duke-libraries/status

Added public methods `Ezid::Identifier#unavailable!` and `Ezid::Identifi...
Metadata element accessors are no longer explicitly defined;
instead the element registry is used through #method_missing.
Custom element accessors can be registered (closes #13, closes #25).
Merge pull request #30 from duke-libraries/metadata-method-missing

Metadata element accessors are no longer explicitly defined;
Version 0.10.0
Merge branch 'release-0.10'