API for new accounts (WebIDs).

[deiu]

The server needs a way to issue certs and create profile documents for new users.

An clear issue right now is how/where to serve the API, since the server does not have a restricted URI namespace for application-specific logic such as the API. Basically what URI will the API have, without actually polluting the data URI namespace. A possible solution to the namespace issue could be the use of the ".well-known" namespace.

A starting point would be to "port" the API from https://github.com/linkeddata/ldphp.

Related to #13.

[deiu]

We discussed having a ,system/ namespace where we put all the APIs. The server would then add a Link header pointing to this namespace, with rel="system".

[deiu]

Implemented in 1c30f4e