iitzco-asapp

Improving error messages in case of double key in config

2

**Is your feature request related to a problem? Please describe.** When certain configs have a duplicate key in the config, then `flambe` fails with: ``` ruamel.yaml.constructor.ConstructorError: could not determine a...

Currently, we disabled the tests for a couple of dataset here https://github.com/asappresearch/flambe/pull/126 Once we make Circle CI work with the request for the zip files, we should add them back.

This PR added a new flag https://github.com/asappresearch/flambe/pull/110 that needs unit testing.