cli should accept files in different directory.

[alinbsp]

Hi,
Is there a reason for using the basename instead of the full file name here?

[coveralls]

Coverage remained the same when pulling a41b60b on alinbsp:directory_arg into d501b66 on alongubkin:master.

[Namek]

@alinbsp How does it affect the way it works?

[alongubkin]

Is there a reason for using the basename instead of the full file name here?

Yes - source maps.