Reworking Security

**This is far from complete, and not to be pulled yet**

The code in 2c6ad47 is a first step in reworking the security. It is from a second look at this, back in March. It forms a first pass at separating the current authenticated user from the owner.

A next step would be to remove the authorization decision from the main server code - so that it would be simpler to support different access models.

Even if we don't go as far as extracting this out into a plugin, we should be able to select which form of authentication and access control we wish to use.