Clean up calls to run benchmarking

[briangow]

In #36 we provide the option to run benchmarking by either passing a single file or point to a CSV control file. This could be cleaner if we only requested the user point to a folder and the code would know how to:

• pull a single file from the folder
• pull multiple files from the folder
• pull files of different types from the folder

or

• use a control file within the folder to know which files and formats to run