A basic test of passing input_json to a container and making sure it comes through

[mccalluc]

Something else might be covering it, but this test had to be removed because we no longer support input via mounted files.

    # TODO: We're no longer writing the input straight to disk:
    #       Instead we need to test with an image that reads the envvars
    # def test_container_spec_with_input(self):
    #     url = self.start_container({
    #         'input': {'foo': 'bar'},
    #         'container_input_path': '/usr/share/nginx/html/index.html'
    #     }).url
    #     self.assert_loads_eventually(url, '{"foo": "bar"}')