pytest-module fails if file path has a space in it

[alxempirical]

https://github.com/ionrock/pytest-el/blob/master/pytest.el#L118

(mapconcat (lambda (test) (substring test (string-width where)))
           (split-string tests) " ") ""))

E.g., (pytest-module "/Users/alx/Google Drive/alien/probcomp/bayeslite/tests/tests/test_bdb.py" nil) results in Args out of range: "/Users/alx/Google", 49, nil.

It should probably check whether tests is a list, and use that in place of the split-string output if so.

[ethanluoyc]

This is introducing a bug with pytest-one, see #14

[Wilfred]

I think this can be closed now that #12 is merged.