The name of human score column in RSMPredict

[from JIRA] The human_score_column in RSMPredict is by default set to 'sc1' when processing the .json file and there is no way to distinguish later in the code whether the user explicitly specified that `sc1` contains human scores.

When we check whether we need to copy over human scores, we simply check whether the human_score_column is present in the data. If a user set human_score_column to 'sc1' but forgot to include it, the tool will not raise an error and will proceed as if no human_score_column was specified.

This does not affect any of the predictions (we only use that field to copy over other values) but should be fixed at some point in the future.