Specifying directories in a test suite EDN

[jennet]

e.g.

{:rdf-cube ["qb"]
}

Currently if a test suite refers to a directory instead of a file, the validator tries to run qb as if it's a file and returns the error

1 /file/path/to/rdf-validator/queries/qb: ERRORED
	queries/qb (Is a directory)

We should either:

• handle the error when parsing the test suite, and report a user friendly error message
  or
• get all the files contained within the directory and load them into the map of files to run