More functionality and bug fixes

I noticed the drag-drop not working this afternoon.  I think this is fixed. 

Take a look at the calendar now.  I put up a red bar (which appears everywhere now, but I don't like this) and a message to view it in week view.  I'm trying to brainstorm about a good way to present the information for say 10 HW sets that are open.  

I did add the popover to the bars to the calendar also.  

1. added improvements to Calendar in reference to issue #7. (not closing yet though)
2.: Added popover to open assignments on the calendar.
3.: Hopefully fixed issue #11.
4.: allowed all set view to have a table that can be sorted (not currently working for the date columns).

Peter