Allow to have more fine grained configuration on the consumer, producer and admin used by canary

[ppatierno]

Currently the canary uses consumer, producer and admin Sarama client with some hard-coded parameters (session timeouts, heartbeat, and more).
It would be useful allow to have a more fine grained control on them in order to change their configuration in different environment where the canary is running (i.e. considering network latency and so on).
As suggested in #166 an "optional" configuration file could be used for that as well, maybe using some specific prefix as consumer., producer. and admin. to define the parameters to change on them.