Updating vs replacing molecules via the HTTP API

[MaybeJustJames]

Currently there is POST /api/v1/metabolites/new. The HTTP RFC defines the POST method like so:

The POST method is used to request that the origin server accept the
entity enclosed in the request as a new subordinate of the resource
identified by the Request-URI in the Request-Line. POST is designed
to allow a uniform method to cover the following functions:

 - Annotation of existing resources;

 - Posting a message to a bulletin board, newsgroup, mailing list,
   or similar group of articles;

 - Providing a block of data, such as the result of submitting a
   form, to a data-handling process;

 - Extending a database through an append operation.

And the PUT method like so:

The PUT method requests that the enclosed entity be stored under the
supplied Request-URI. If the Request-URI refers to an already
existing resource, the enclosed entity SHOULD be considered as a
modified version of the one residing on the origin server. If the
Request-URI does not point to an existing resource, and that URI is
capable of being defined as a new resource by the requesting user
agent, the origin server can create the resource with that URI. [...]

Therefore the metabolite submission API should be something like, PUT /api/v1/metabolite/ALPHA-GLUCOSE and should create if it doesn't exist, or update if it does exist. There should also be a version field and a submission date field in the database.