Create BEL Evidence from supported BEL formats

[abargnesi]

A POST /api/evidence should allow for BEL Evidence to be created from a request body with supported media types:

Format	Media Type
BEL Script	application/bel
XBEL	application/xml
JGF	application/vnd.jgf+json
RDF	application/n-quads, application/n-triples, application/rdf+xml, application/turtle, application/x-turtle, text/turtle

We should return a 201 status with Location header pointing to a dataset resource. This dataset would allow users to retrieve all Evidence described in the POST-ed dataset.

We should process the request body without buffering in memory.

In this case it is valid to return a 201 with dataset resource as all evidence will eventually be processed.