Fix error when marshalling null list.
Allow properties to be used with fields.Nested.
Fix bug that prevented fields.Nested from picking up values that are properties on the object being marshalled.
Fix broken test

Flask 0.10.1 added an assertion for unique endpoints, which broke our tests.

This makes the test endpoints unique, so it gets by the assertion. In the future,
we might want to consider freezing our requirements.
Merge branch 'fix-nested-value-access' of git://github.com/davidcrawford/flask-restful into davidcrawford-fix-nested-value-access
Merge pull request #88 from davidcrawford/fix-nested-marshal

Fix error when marshalling null list.
Merge branch 'master' of https://github.com/twilio/flask-restful