Why is Memory benchmarking disabled ?

I noticed that **memory benchmarking** is disabled in the library.

```elixir
if mem_stats or sys_mem_stats do
log ">> 'mem stats' flag is currently ignored"
end
```
Are there any problems with the current logic ?
I am ready to work on them and fix them, but will need some help.

Also, Is this calculation correct ?
```elixir
mem_used = mem_after - mem_before
```