This patch proposes a decorator to be used to profile code with
cProfile. Config options are added to control whether the code is
profiled or not. The default is no profiling performed.
The decorator is then used in the Neutron API base and Pecan controllers
for the index, show, create, delete and update operations. The rpc_loop
method of the OVS agent is also decorated.
Finally, profiling is enabled for neutron-rally-task.
Change-Id: I5c847a255b4b973add7fce5a38a2594912c491ac
eb3302207f