Add the ability to unwatch from RPC API

boolean removePageWatch(String token, long pageId) - remove a page or blog post watch as the current user, returns false if the space, page or blog isn't being watched
boolean removeSpacewatch(String token, String spaceKey) - remove a space watch as the current user, returns false if the space isn't being watched
boolean removePageWatchForUser(String token, long pageId, String username) - remove a watch on behalf of another user (space administrators only)