Network check fixes

- Proper network mapping
- Proper reclass lookup
- VIP detection
- Simple error gathering
- IP shown as 'exploded', i.e. in CIDR format
- MTU matching and detection
- Errors class for handling errors, including codes and indices
- Summary and detailed errors view
- Flake8 refactoring

Change-Id: I8ee37d345bdc21c7ad930bf8305acd28f8c121c8
Related-PROD: PROD-28199
diff --git a/cfg_checker/modules/reclass/validator.py b/cfg_checker/modules/reclass/validator.py
index e7d7f06..8fc65a5 100644
--- a/cfg_checker/modules/reclass/validator.py
+++ b/cfg_checker/modules/reclass/validator.py
@@ -2,6 +2,7 @@
 
 from cfg_checker.common import logger_cli
 
+
 def basic_model_validation_by_path(path):
     logger_cli.debug("\t...validating '{}' as a model".format(path))
     _checks = []
@@ -20,7 +21,7 @@
     _has_nodes = os.path.isdir(os.path.join(path, "nodes"))
     logger_cli.debug("\t- has nodes? -> {}".format(_has_nodes))
     _checks.append(_has_nodes)
-    
+
     logger_cli.debug("\t-> {}".format(
         all(_checks)
     ))