Assembly factory can create an arbitrary number of products w/ trait

Change-Id: I84339a20dd81acf4787f8ef0df1423bc757c05c2
assembly factory accepts a hash of variant => quantity
sync assembly inventory

Change-Id: I69bdace7e8ceb3e442d593cb4eba2b1147441e2f
Merge pull request #6 from Dkendal/update_assembly_inventory

Update assembly inventory