Fix OOBI contact generation

[pfeairheller]

This PR fixes #922 by reintroducing contact creation since it is optional. It also includes a few minor logging fixes.

[kentbull]

From one of our calls we discussed changing:

self.org.replace(pre=obr.cid, data=dict(alias=obr.oobialias, oobi=url))

to

self.org.update(pre=obr.cid, data=dict(alias=obr.oobialias, oobi=url))

Because Organizer.update() performs a Organizer.replace() if the contact data doesn't exist yet if it does exist then it performs a merge, which is what Fergal was after anyway. What was causing people problems is that `Organizer.replace() wipes out any contact data that is there, which will always erase any aliases you have for someone if you re-oobi with them without specifying the alias.

I'll open up A PR for this.