add support for dynamic validation schemas for resources: using a property the schema can now be determined depending on the view context or request, for example
Merge remote-tracking branch 'mozilla/master' into schema-factories

Conflicts:
	CHANGES.txt
add test for e9cc04a7b0b5e0851b20cec78429e3f9db452255
cosmetics: only call `validate_colander_schema` in one place
Merge remote-tracking branch 'mozilla/master' into 'schema-factories'

* mozilla/master: (29 commits)
  Fixing JSON syntax in tutorial example
  Update tutorial.rst
  Fix a typo in the Service docstring
  Rename Request to MockRequest
  Bump version
  populate the CHANGES.txt file
  Overwrite pyramid default exception handling.
  Manually commit configuration changes. Fixes #151.
  Add support for Colander's drop object.
  implement "415 Unsupported Media Type" (validate "Content-Type" request header) on top of Pyramid's predicate system
  Enhance docs for class-level validators / filters.
  Test that the email colander field works.
  Update the sphinx directive documentation.
  Fix py3k compatibility, improve style & comments.
  Allow Colander schemas with sequence fields in querystring
  Remove PasteScript from the Cornice template.
  silence deprecation warnings on py3k: renamed "assertEquals" to "assertEqual"
  use @ryansb link - much better - fixes #139
  moved to a still-existing link
  Fix typo in docstring (list -> tuple)
  ...

Conflicts:
	CHANGES.txt
	cornice/tests/test_resource.py
revert 04242358 as otherwise passing `schema=None` (in `args`) would shadow any schema on the object
document how to use dynamic schemas
Merge pull request #162 from pyfidelity/schema-factories

add support for dynamic validation schemas for resources