Add road_direction property to FieldDeviceCoreDetails

[j-d-b]

This PR resolves #250 by adding a road_direction property to the FieldDeviceCoreDetails object. Specifically, the following changes were made:

• Add optional road_direction property to the FieldDeviceCoreDetails object.
• Move the "Direction" JSON Schema type definition to it's own JSON file and generalize its description.
• Reference the moved "Direction" type from SwzDeviceFeed.json and RoadEventFeature.json.

As more enumerated types are shared between feeds, we can consider further organization of the JSON schema files.

[sknick-iastate]

The only minor change I see is that the FieldDeviceCoreDetails needs to be added to the used by section of the Direction enumerations. Everything else looks good.

[eli104]

I apologize if this comment is late to the discussion, and/or if it's already been discussed elsewhere: I notice on the Direction Enumeration that the values are based on TMDD link-alignment Enumeration... which itself also notes "inner-loop" and "outer-loop" to help refine the direction of the road flow.

Are these additional attrobutes something that have, or should be, considered? Perhaps under Direction or perhaps in the RoadEventCoreDetails (further enhancing the requirements of the "road_name")?

Reasons:

• A location (automatically from a device) may not be accurate when inner/outer roadways are nearly parallel, or when other road beds provide the same geographic location (such as upper and lower bridge decks, e.g. the George Washington Bridge and others in NY/NJ).
• The same may be true for a manually entered location, meaning the direction alone may not provide clarity in if the "inner/outer" or "upper/lower" roadway is not specified.

Again my apologies if this has already been discussed (or if the discussion needs to move somewhere else... so be it).

[j-d-b]

@eli104 see #324—the discussion can be continued there.

[j-d-b]

The only minor change I see is that the FieldDeviceCoreDetails needs to be added to the used by section of the Direction enumerations.

@sknick-iastate Thank you, fixed and pushed.