The maximum cap parameter triggers errors when implemented form the simulation server. This is an attempt to fix the problems

Changes proposed in this pull request:

• OPTIMIZED_ADD_CAP replaced by "optimized_add_cap" in the assets keys returned to EPA after simulating
• The if statement for adapting MAXIMUM_CAP for non-dispatchable production assets is now based on the value of DISPATCHABILITY and not on the existence of the key FILENAME in the asset_dict
• "maximum_add_cap" to the keys returned to EPA after simulating got production assets

The following steps were realized, as well (if applies):

• Use in-line comments to explain your code
• Write docstrings to your code (example docstring)
• For new functionalities: Explain in readthedocs
• Write test(s) for your new patch of code (pytests, assertion debug messages)
• Update the CHANGELOG.md
• Apply black (black . --exclude docs/)
• Check if benchmark tests pass locally (EXECUTE_TESTS_ON=master pytest)

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