Reviewed by Adam Barth.

        Display queue position inside EWS bubbles
        https://bugs.webkit.org/show_bug.cgi?id=38979

        This ended up being a lot of clean-up to our status server code.

        Added a new WorkItems model, a form with which to fill it,
        and taught the Attachment class how to calculate the current queue
        postion for an attachment using the data in WorkItems.

        I also finally made statusbubble.* and dashboard.* not use copy-paste code.

        The Attachment class has this summary() method which is very
        controller/view-like and does not belong in a model class.
        This patch got rid of all direct uses of summary().

        * QueueStatusServer/handlers/dashboard.py:
          - Build row objects to hand off to the view instead of handing off a
            summary object and expecting the view to process it directly.
        * QueueStatusServer/handlers/statusbubble.py:
          - Build bubble object and hand them off to the view.
        * QueueStatusServer/handlers/updatestatus.py:
          - Code cleanup.  Just move some code into _queue_status_from_request
            to make the main put() handler easier to read.
        * QueueStatusServer/handlers/updateworkitems.py: Added.
          - Controller to handle storing WorkItems model objects.
        * QueueStatusServer/main.py:
          - Add route for /update-work-items
        * QueueStatusServer/model/attachment.py:
          - Add new methods to replace direct summary() access.
          - Teach attachment how to calculate queue positions from WorkItems data.
        * QueueStatusServer/model/queues.py:
          - Move name_with_underscores here for easier re-use.
        * QueueStatusServer/model/workitems.py: Added.
         - New model for storing what items are currently queue for any bot.
        * QueueStatusServer/templates/dashboard.html:
         - Kill the copy/paste code!
        * QueueStatusServer/templates/statusbubble.html:
         - Kill the copy/paste code!
        * QueueStatusServer/templates/updateworkitems.html: Added.
         - Simple form for updating a queue's current work items.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@59534 268f45cc-cd09-0410-ab3c-d52691b4dbfc