Combine size and UOM for "size" column in export

rattail_corepos/corepos/importing/db/exporters/catapult_inventory.py

@@ -407,11 +407,13 @@ class InventoryItemImporter(FromCore, catapult_importing.model.InventoryItemImpo
             if self.exclude_missing_department:
                 return
 
-        size = product.size
+        size = "{} {}".format((product.size or '').strip(),
+                              (product.unit_of_measure or '').strip())
+        size = size.strip()
         # TODO: this logic may actually be client-specific?  i just happened to
         # find some of these chars in a client DB and needed to avoid them, b/c
         # the openpyxl lib said IllegalCharacterError
-        if size is not None and '\x00' in size:
+        if '\x00' in size:
             logger = log.warning if self.warn_size_null_byte else log.debug
             logger("product %s has null byte in size field: %s",
                    product.upc, product)