Ardere config should allow "_" and "-" in name param

[rpappalax]

ardere chokes if name param is other than alpha. I think we could disallow spaces, but we should at least allow underscores, dashes.

LambdaFunctionFailed
{"error":"ValidationException","cause":"{\"stackTrace\": [[\"/var/task/handler.py\", 13, \"populate_missing_instances\", \"return runner.populate_missing_instances()\"], [\"/var/task/ardere/step_functions.py\", 190, \"populate_missing_instances\", \"self._validate_plan()\"], [\"/var/task/ardere/step_functions.py\", 179, \"_validate_plan\", \"raise ValidationException(\\\"Failed to validate: {}\\\".format(errors))\"]], \"errorType\": \"ValidationException\", \"errorMessage\": \"Failed to validate: {'steps': {0: {'env': [u'Not a valid mapping type.']}}}\"}"}