Merge pull request #657 from caphrim007/bugfix.requests-2.11-support

Make transaction IDs strings to work with python requests 2.11

Author: zancas

f5/bigip/contexts.py

@@ -50,7 +50,7 @@ def __enter__(self):
         self.transaction = self.transaction.create()
 
         self.icr.session.headers.update({
-            'X-F5-REST-Coordination-Id': self.transaction.transId
+            'X-F5-REST-Coordination-Id': str(self.transaction.transId)
         })
         return self.bigip