Set batch options for internal sync

Allows an operator to set batch_size and batch_count for internal push replications to a specific node via config:set.
Also move the case config to a new indentation level on a new line when you do.

Also background since this is subtle, adding a case here means that the case statement is entirely in the try/catch scope. Without that then your `catch _:_` statement is *only* catching exceptins thrown from the config:get/3 call. If the list_to_integer/1 failed it wouldn't be caught as you're expecting it to.