Allow the user to compare sites

We need to add a new tool to Inventory section that allows the user to select site1 and site2 and specify AccessionFilters. GGCE will then display a table:

Accession	Site 1	Site 2
TMe-419	2	0

Columns site1 and site2 contain the number of inventories (quantityOnHand > 0 and formTypeCode != '**') at that site.

Additional filters should allow the user to specify the number range of the two values.