Allow __DEFAULT under __PATH for catch-all-else paths

[Mardak]

I'm not sure if this is the expected behavior or if it's intended to match subsections that aren't explicitly listed. E.g., "arts" has 4 explicit subsections plus __NONE, and there's no explicit match for "dance" which could be classified as "Arts".

http://www.nytimes.com/2014/01/27/arts/dance/a-giant-photo-connects-fans-to-ballet-stars.html

Results in an article object with labels: []

[oyiptong]

Yes, that was the intended behavior, so as to create a precise, albeit verbose, mapping

[oyiptong]

I suggest another operator, inside of PATH: "DEFAULT", which matches all except the cited paths and __NONE

[Mardak]

Updated issue summary to allow for a default label if none of the explicit paths matched.

[Mardak]

Added Arts as a default under arts. https://github.com/oyiptong/up-headliner/commit/207b2483818252708f3064e40b82e02bf60dedb6