Directories should appear as something other than application/octet-stream

[watzon]

There is a depreciated definition for a mime type of text/directory which could be used if there aren't any other ideas. I feel like it would be a good idea to have something other than application/octet-stream since there will be times when a user want's to differentiate between a directory and a binary file.

[broofa]

Doing a bit of issue housekeeping. This module doesn't do filesystem stat'ing (and won't anytime soon), so no way to know if a path is a directory or not. But, agreed that application/octet-stream probably shouldn't be the default. See #139.