Refactors `nomad fs` command to eliminate `fs` subcommands.
Automatically displays the file, if the path specified is a file; lists
the directory if the path is a directory; or displays stat information
if the `-stat` flag is set.

Currently running `nomad fs ls` to find a file, then running the exact
same command with the exception of `cat` instead of `ls` is time
consuming and awkward. This allows operational testing to be greatly
enhanced, and makes our lives so much better.