added /api/datasets routes
added /api/datasets routes

POST /api/datasets
------------------

A BEL document must be POSTed to /api/datasets to create a dataset and
the evidence it contains.

The BEL document should be one of the following stable formats:
- bel_script    (media_type - application/bel)
- xbel          (media_type - application/xbel)
- json_evidence (media_type - application/json)

A 201 will result with the Location header of the created dataset.

A 409 (Conflict) will result when the BEL document already exists by
document "Name" and "Version" (i.e. identifier, "NAME/VERSION"). In
this case the conflicting resource will be included in the response.

GET /api/datasets/{id}
----------------------

Returns a single dataset (VoID data).

GET /api/datasets
-----------------

Returns all datasets (VoID data).

DELETE /api/datasets/{id}
-------------------------

Deletes a single dataset and all of its evidence. This is currently slow
due to inefficient mongo removal.

OpenBEL/openbel-api,OpenBEL/openbel-server,OpenBEL/openbel-server,nbargnesi/openbel-server,OpenBEL/openbel-api,nbargnesi/openbel-server,nbargnesi/openbel-server,OpenBEL/openbel-api,OpenBEL/openbel-api,OpenBEL/openbel-server