add max_rpm_per_host

What will happen if your initial list will contain an odd number of elements (ex. [1,2,3] instead of [1,2,3,4])? 

```erlang
redis_response_to_tuple_list([Host, Count | T]) ->
  [{Host, binary_to_integer(Count)} | redis_response_to_tuple_list(T)];
redis_response_to_tuple_list(_) ->
  [].
```