Cornice

**Bug fixes**
- Fix Colander imports to make sure it remains optional (400)
- Fix truncated JSON validation error message when request body does not contain
valid JSON (401)
- Fix docs about upgrading deserializers (402)

**Breaking changes**

Please refer to [upgrading docs](http://cornice.readthedocs.io/en/latest/upgrading.html) for detailed migration instructions.
- Dropped Python 2.6 support (368)
- Got rid of Buildout files (369)
- Got rid of Spore extension (379)
- Moved Sphinx extension to dedicated repo (379)
- Moved project scaffold to dedicated repo (238, 390)
- Completely rework the schema validation features (376, 386)
- Moved examples to dedicated repo (392)
- Custom `error_handler` now receives the request instead of errors (381)
- Errors list `request.errors` has no `request` anymore (372, 378)
- `request.errors.add()` now only accepts one of `header`, `body`, `url`,
`path`, `querystring`, `cookies` or `method` as first argument (374)
- Remove deprecated features (382)

**Internal changes**
- Take `__version__` from setup.py (358)
- Remove duplicated list of test deps in tox file (371)

Bug fixes
- Properly handle content_type callables returning a single internet media type
as scalar. Thanks amotl (343)
- Do not raise a 415 error when no content-type and no body (354)

Documentation
- Improve documentation regarding content type negotiation and media type
validation. Thanks amotl (91, 343, 350)
- Fix typo in testing docs. Thanks peletiah (348)
- Clarify docs for deferred colander validator. Thanks antoineleclair (352)

- Adding the ability to define services imperatively. (335)
- Clean cornice/statics/ files. (345)

Bug fixes
- Convert `None` to `colander.null` before calling colander's `deserialize` function. (342)
- Allow i18n of colander error messages (206)

- Warn if resource collection and record paths are not distinct. Thanks
circlingthesun (292)

Bug fixes
- Fix duplicated CORS exposed headers (301)
- Fix setup.py in template. Thanks areski (296)
- Make resource test less dependent on Pyramid version (312)
- Fix reload in sphinx extension for Python 3. Thanks JohnBrodie (295)
- Fix usage of Colander `schema_type()` and `schema.typ`. Thanks
tisdall (309)
- Fix check for CORS Allow Credentials. Thanks treerao (320)
- Fix Access-Control-Max-Age value if undefined on service (338)

Documentation
- Fix typos in documentation. Thanks robvdl, tisdall (306, 313)
- Rewrite quickstart documentation (305)
- Huge set of documentation improvements. Thanks areski (297)

Breaking changes:
- ACLs are now handled per route and not per view. Thanks circlingthesun
(287)

Other changes:
- Display default values in the sphinx documentation extension, Thanks
MikaYuoadas (284)
- Add an option to disable Colander schema request binding. (288)