Sort cards in Board Calendar view by due date OR allow manual sorting

Issue Summary

Right now, cards are sorted by the order in which they are located in a list and where that list sits within a board. There's currently no way to change that.  

Steps to Reproduce

1. Create a card and set the Due date and time 
2. Create another card below the previous one in the same list 
3. Set a due date on the same day as the first card but a few hours earlier 
4. Open the Calendar view

Expected Results

You see cards ordered according to the due date and time. 

Actual Results

Cards are sorted by their location in a list. 

Workaround

Sort cards in list by due date.