jp (pubsub): added affiliations and node/affiliations/get: affiliations allow to retrieve all node were a profile is affiliated on a service, or the affiliation on a specific node. node/affiliations/get is for node owner and allow to retrieve who is affiliated with a node and which kind of affiliation.

Use this module to temporary store files that need to be integrated to other
projects such as Wokkel.

For example, the changeset that introduced this folder adds RSM (XEP-0059)
support to Wokkel. The files in sat.tmp.wokkel are imported over the initial
wokkel files from sat.plugins.__init__.py