* Fix has_complete_bom_pricing logic errors
There are two logic errors in this property method that have been present since
c6fd228.
1) The get_setting method needs to be called on the InventTreeSetting class in
common.models, not on the module itself.
2) You cannot call a property method directly passing an argument in Python, so
the call to has_pricing_info is invalid and always fails. Given that
has_complete_bom_pricing is/was the only user of that property anyway, fix
this by just internalising the logic from that property in the method
directly.
* style nit: use implicit checking for bools
has_complete_bom_pricing is a boolean property, the preferred pythonic style
for if comparisons of this type is not to complete directly to == False, etc
and rely on the implicit truthiness of the type.
