Added data CSV file not used in training

[blackvvine]

I noticed that when running the train command, the "added data" CSV file classification_tools/data/training_data_added.csv is not actually appended to the "original" training dataset:

rcATT/classification_tools/__init__.py

Line 70 in f82f7fd

train_data_df.append(train_data_added, ignore_index = True)

Note that the Pandas DataFrame.append function returns a new DataFrame and does not modify its input, so the corrected version would be:

	train_data_df = train_data_df.append(train_data_added, ignore_index = True)

I'd be happy to submit this as a merge request, if that'd work.