[higgins-dev] Refactoring persona.owl

[Paul Trevithick <ptrevithick@xxxxxxxxx>]

1. Refactoring

I decided to reorganize persona.owl by moving all the context-related classes & attributes into a new sub-vocabulary, context.owl. 

All OWL files and wiki pages have been updated. See
* http://wiki.eclipse.org/Persona_vocabulary
* http://wiki.eclipse.org/Context_vocabulary (NEW)

2. Additions to Context vocabulary

New classes: SharingPolicy (and subclasses WhiteList and AccessControlList), Website.
New attributes: sharingPolicy, member.

The above allows a context to either use its "control" context to define its sharing and access control policy OR (ad this is the new part) it allows the context to say that it is using an (external) PDS-operator managed white list of websites.