objecthash 0.4.0

## 0.4.0 (2017-01-16)

* Rename `objecthash_struct_member!` to `objecthash_member!`
* Do not automatically create references from objecthash macro args
* Remove associated digest type from ObjectHasher trait. Always use
  objecthash::Digest instead

## 0.3.0 (2016-08-21)

* `objecthash_struct_member!` macro

## 0.2.2 (2016-08-21)

* Coerce `objecthash_struct!` key names to Strings

## 0.2.1 (2016-08-21)

* Bugfix for `objecthash_struct!` macro

## 0.2.0 (2016-08-21)

* Add `objecthash_struct!` and `objecthash_dict_entry!` macros

## 0.1.1 (2016-08-15)

* Add the newly released *ring* crate as an optional dependency

## 0.1.0 (2016-08-08)

* Initial release