config.py: Allow escaping commas in parametrized scenario names

comma character ',' is used in the command line to split between
parameters, which means a parameter value itself couldn't contain it.
This commit allows passing a comma inside a character value by escaping
it with '\,'.

Change-Id: Ic0bd9a029137a59e8c4a32b807eba7a64fcfa51f
1 file changed