Add N2VCNotFound exception

Change-Id: I83702862086996adaefbfb9721f08f40bc943a44
Signed-off-by: David Garcia <david.garcia@canonical.com>
diff --git a/n2vc/exceptions.py b/n2vc/exceptions.py
index a663c62..815d4ea 100644
--- a/n2vc/exceptions.py
+++ b/n2vc/exceptions.py
@@ -125,6 +125,18 @@
         return '<{}> Invalid certificate: {}'.format(type(self), super().__str__())
 
 
+class N2VCNotFound(N2VCException):
+    """
+    Not found
+    """
+
+    def __init__(self, message: str = ''):
+        N2VCException.__init__(self, message=message)
+
+    def __str__(self):
+        return '<{}> Not found: {}'.format(type(self), super().__str__())
+
+
 class K8sException(Exception):
     """
     K8s exception