Feature/train test filename

This pull request addresses the following issue:

"Train/test requires feature files to have the same name but in different directories". #12

This PR reflects changes made based on the initial code review when the PR was originally submitted to the develop branch.  (For tracking purposes, the original name of the PR was "Added support for use case in which user submits single training and testing files via train_file and test_file in the configuration file.")