Wiki pages are now autosaved

WikiPage now autosaves, with a delay of 30sec.
A "draft" property is now used to indicate when the user is still editing.
A filter prevents draft pages from being pushed to the server.
Made page member list editable

...as long as you're the page owner.

Adding a member to a page also adds her to the member list of the
page's wiki, if necessary.
Use channel-based sync (i.e. Couchbase Sync Gateway)