Add verbosity level to medusa

[aviggiano]

I'd like to have different verbosity levels for Medusa. Right now, it can show some useless information if it rungs for long hours:

fuzz: elapsed: 15s, calls: 45776 (4602/sec), seq/s: 46, coverage: 149
fuzz: elapsed: 18s, calls: 61164 (5129/sec), seq/s: 51, coverage: 161
...
fuzz: elapsed: 59m55s, calls: 18366977 (4982/sec), seq/s: 49, coverage: 482
fuzz: elapsed: 59m58s, calls: 18382831 (5284/sec), seq/s: 52, coverage: 482

I would like to have a verbosity mode that only shows elapsed time, not every 3s

[aviggiano]

Duplicate of #204