Reverts 18c033dc5c00b2ce0b3528cb310bf3988377e39f

The merge that is reverted assigned categories to posts
based on the subfolders in the _posts directory and 
was merged under the understanding that it was fixing a bug.

Subfolders in the _posts directory should not assign 
metadata information to posts at this point in time and 
was not a bug.
Reverted deleted test and modified ensure subdirs are ignored.
Fixed ignore subir test.
Merge pull request #2705 from bcomnes/dont_read_categories_from_path