Resolve "keys should not contain information in ewoks representation"

Closes #10 (closed)

To make sure all dictionaries in an ewoks representation have fixed keys, the following changes have been made:

Arguments

This

"arguments": {"a": "return_value"}

will be replaced by this

"data_mapping": [{"target_input": "a", "source_output": "return_value"}]

Inputs

This

"inputs": {"a": 1}

will be replaced by this

"default_inputs": [{"name": "a", "value": 1}]