Manually commit configuration changes. Fixes #151.
Overwrite pyramid default exception handling.

Using context=Exception wasn't catching the HTTPNotFound and HTTPForbidden
cases. That's still a mistery why the tests were passing without this change,
however.

This fixes CORS support for 404 and 403.
populate the CHANGES.txt file
Bump version
Merge pull request #152 from abrookins/manually-commit-configuration-changes

Manually commit configuration changes. Fixes #151.
Merge branch 'master' of https://github.com/mozilla-services/cornice into colander-drop-support