fix: the excerpt of page wasn't updated (#62)

When the page was handled by processors, the page excerpt was not
updated, and keep the old excerpt of the page. The solution is to
update the page excerpt by checking whether the page is handled by
any one of processors.

Author: jeffreytse

lib/jekyll-spaceship/cores/manager.rb

@@ -58,13 +58,20 @@ def self.is_hooked?(container, event)
     end
 
     def self.dispatch(page, container, event)
+      # dispatch to each processor
       @@_processors.each do |processor|
         processor.dispatch page, container, event
         break unless processor.next?
       end
       if event.to_s.start_with?('post') and Type.html? output_ext(page)
         self.dispatch_html_block(page)
       end
+      # update page excerpt
+      @@_processors.each do |processor|
+        next if not processor.handled
+        break page.data['excerpt'] = Jekyll::Excerpt.new(page)
+      end
+      # call on_handled
       @@_processors.each do |processor|
         processor.on_handled if processor.handled
         break unless processor.next?