Update command line options and tutorials

[ntadimeti]

val_files -> files_val
train_files -> files_train
sizes_files -> files_chromsizes
intervals_file -> file_intervals

[tijyojwad]

@ntadimeti another thing we should clarify in README that API in master branch could be different from API in development branch. So the configs from AWS may not work with both. Or if we make a breaking change then we should specify that tutorial only work for master branch

[ntadimeti]

@tijyojwad added a note in the readme about compatibility of tutorials with master branch

[ntadimeti]

Closing this PR since a lot is changing wrt to APIS and tutorials. This is obsolete.