Add some minor migrations
Change the footer to be at the bottom all the time
Add ajax endpoint to get BoM for all material used in a blueprint
Add sub comp BoM display in the correct tab

- Load the list of materials, with their bill of materials, used in the
current blueprint.
- The list is only loaded once (ajax call) when switching tab for
performance (as we may not want to see it)
- Also some UI improvements (looks cleaner than before)
- Close #6