Add new parser implementation, give references item-creating powers
Add Flask-Testing to setup requirements
Specify Flask-Testing version
Change setup_requires to tests_require in setup.py
Change required Flask version. Must be >=0.10 now.
Add (bulk) relationship object creation
Implement two-phase parsing for bulk and embedded object creation
Rename 'resource_uri' to '_uri' in JSON objects

"_uri" is more compact. The initial underscore clearly highlights it as metadata and this pattern should be used with any new metadata to be added. There is the possibility of adding "_id" later on without risking a clash with fields named "id" or similar.
Rename "resource_uri" to "_uri" in comments
Refactor NestedProxy types to ResourceRoute and refactor schema

- Schema now split between API/Resource/Field levels
- ResourceMethod now ResourceAction
- SchemaParser to replace flask_restful's RequestParser
Clean-up schema definition and parsing
Fix Python 2.7 support; clean-up
Remove all references to Flask-RESTful's RequestParser

Use SchemaParser() instead from now on.
Update signals: remove filter signals, rename 'relationship' signals to new method names.
Fix unit tests
Remove PresstApi.enable_schema() now on by default
Update documentation
Rename PresstResource to Resource
Add PrincipalResource initial

New resource type for mixed Object and Role-based permissions
Respond with 200 but empty list when read permissions return empty query