Don't duplicate last published PEP items

When a contact becomes available, usually both the 'caps_update' hook
and the 'presence_probe_hook' are called.  For remote contacts, both
hooks triggered PEP notifications, so each item was sent twice.  Fix
this by ignoring the 'presence_probe_hook' for remote contacts.
Merge pull request #352 from weiss/no-last-pep-duplicates

Don't duplicate last published PEP items