Consolidate on 'pk' as the ID field in the API

InvenTree/company/api.py

@@ -152,7 +152,7 @@ supplier_part_api_urls = [
 
 company_api_urls = [
     
-    url(r'^part/', include(supplier_part_api_urls)),
+    url(r'^part/?', include(supplier_part_api_urls)),
 
     url(r'^price-break/?', SupplierPriceBreakList.as_view(), name='api-part-supplier-price'),
 

InvenTree/company/serializers.py

@@ -33,7 +33,7 @@ class CompanySerializer(serializers.ModelSerializer):
     class Meta:
         model = Company
         fields = [
-            'id',
+            'pk',
             'url',
             'name',
             'description',