Use load_inventory instead for load_from_json. Rename
load_from_json to _load_from_json.
Move most of the --clear-ip and --remove calls to their
corresponding functions. Modified other calls to account
for the change
Add a test to test for inventory item removal.
fixes bug: 1663328
Change-Id: I2dbecb085383b3d02e298cc09b02566d1e52a064