Update pack view (pretty_bms.html) to match RW-3x pack

[aaronbeekay]

The pack display page should be updated to match the RW-3x pack design:

• The shelf display should be either removed or updated to have seven shelves.
• The maximum and minimum cell voltage calculations should be updated to take into account cells on BIM6.
• The data validity indicator (timeout) should be updated to take into account data from BIM6.

[aaronbeekay]

PR #34 begins to do some of the work on this issue, but the mobile interface still needs to be updated to include the appropriate data. Larsen is responsible for this.