Move SupplierPart and SupplierPriceBreak to the 'Company' app

- https://docs.djangoproject.com/en/2.2/ref/models/options/#django.db.models.Options.db_table
- https://stackoverflow.com/questions/3519143/django-how-to-specify-a-database-for-a-model
- And others, presumably

InvenTree/company/api.py

@@ -12,7 +12,10 @@ from rest_framework import generics, permissions
 from django.conf.urls import url
 
 from .models import Company
+from .models import SupplierPart, SupplierPriceBreak
+
 from .serializers import CompanySerializer
+from .serializers import SupplierPartSerializer, SupplierPriceBreakSerializer
 
 
 class CompanyList(generics.ListCreateAPIView):