Add basic file format feature

Please note that I wrote this with my "business hat" on. There is no thought (and shouldn't be at this stage) on how this will be implemented (some of the options may not be).

The only real reasons to reject this pull request would be:

* If you disagreed with the business direction (this is something I am hoping to solely drive at this point / so this shouldn't happen)

* If you can't get this command to work (although spitting out everything without any defined steps is okay):
    ` behave features/file_formats.feature`

* If I have spelling mistakes/typos in the code. (And I would hope that this is just spelled out so that I could correct instead of rejecting).