Release 1.0.0

* Require registration for YAML constructors & representers -- this no longer
happens automatically as a side-effect of importing the `gryaml` package.
* Add "simple" constructors & representers, to convert Nodes or Relationships
to plain YAML structures or YAML structures tagged with '!gryaml.*' to
plain Python structures.
* Reorganized repo so package is in `src/`.
* Added more tests.
* Use `py2neo_compat` as compatibility layer.

• Commit 96578f2
• Compare 1.0.0
• Tag 1.0.0

Wil Cooley