Fixes Issue #1323 - exists method failing on GTM topology records

Problem: The / and ~ characters are disallowed in sdk URLs

Resolution: Overload the exists method for topology by applying:
  kwargs['transform_name'] = True

Author: f5-rahm

f5/bigip/tm/gtm/topology.py

@@ -146,6 +146,10 @@ def load(self, **kwargs):
 
         return self._load(**kwargs)
 
+    def exists(self, **kwargs):
+        kwargs['transform_name'] = True
+        return self._exists(**kwargs)
+
     def refresh(self, **kwargs):
         """Refresh is not supported for Topology