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/common/exception.py b/cfg_checker/common/exception.py
index 8e8b818..52aab2d 100644
--- a/cfg_checker/common/exception.py
+++ b/cfg_checker/common/exception.py
@@ -31,3 +31,9 @@
     def __init__(self, message, *args, **kwargs):
         super(InvalidReturnException, self).__init__(message, *args, **kwargs)
         self.message = "# Unexpected return value: {}".format(message)
+
+
+class ErrorMappingException(CheckerException):
+    def __init__(self, message, *args, **kwargs):
+        super(ErrorMappingException, self).__init__(message, *args, **kwargs)
+        self.message = "# Unexpected error mapping/type: {}".format(message)