Add an option to predict allowing for a bed file of regions to predict

[mmtrebuchet]

The predict program currently uses input_data.json to both gather task information and get a list of peaks to predict. In the event that I want to train and predict on different regions, this means I have to create a second input_data.json with different bed files. It'd be nice if there were a way to provide a bed file of regions where I want predictions to the predict program, so that I don't have to go through this hoop.