dir should allow multiple

[joscha]

I get the error:

Error: TypeError: Path must be a string. Received [ 'src', 'finders' ]

but my project has source files that are both in src and finders. I propose dir should be able to accept multipel values.

[lipp]

Agree! Thanks for the input! dir will accept a string or an array of strings.

[zandaqo]

I believe using glob patterns is a better solution here. In the long run it's only a matter of time when someone decides that having multiple dirs isn't enough and he needs to include/exclude some files according to a pattern. Allowing to use glob patterns in files parameter would solve this. This PR might work #81