Updates to scripts after refactor

- Run black to reformat all the scripts
- Update makefile test targets, pylint, and fix some of the issues found
- Update pxeconfig script for refactored nbhelper
- Add start of inventory script

Change-Id: I5f426ac2da840dc72f07f8a6844e199e47d49135
diff --git a/scripts/pxeconfig.py b/scripts/pxeconfig.py
index 97aedab..fe9e1a7 100644
--- a/scripts/pxeconfig.py
+++ b/scripts/pxeconfig.py
@@ -11,7 +11,6 @@
 from __future__ import absolute_import
 
 import nbhelper
-
 from ruamel import yaml
 
 # main function that calls other functions
@@ -28,24 +27,25 @@
     }
 
     args = nbhelper.initialize(extra_args)
-    tenant = nbhelper.NBTenant()
+    tenant = nbhelper.Tenant()
 
     yaml_out = {}
     pxeboot_hosts = []
 
-    prefixes = nbhelper.NBPrefix.all_prefixes()
-    devices = nbhelper.NBDevice.all_objects()
-
-    for dev_id, device in devices.items():
+    for device in tenant.get_devices():
 
         # only pxeboot for servers
-        if device.data["device_role"]["slug"] == "server":
+        if device.data.device_role.slug in ["server", "router"]:
 
             pxe_dev = {}
-            pxe_dev["serial"] = device.data["serial"]
             pxe_dev["hostname"] = device.data["name"]
             pxe_dev["domain"] = args.domain_extension
-            pxe_dev["mac_address"] = device.primary_iface()["mac_address"].lower()
+
+            if device.data["serial"]:
+                pxe_dev["serial"] = device.data["serial"]
+
+            if device.primary_iface["mac_address"]:
+                pxe_dev["mac_address"] = device.primary_iface["mac_address"].lower()
 
             pxeboot_hosts.append(pxe_dev)