Support non-exception nonblocking I/O

[nateberkopec]

Since Ruby 2.3, nonblocking I/O methods take exception: false, so they no longer have to raise exceptions when they would block.

redis-rb/lib/redis/connection/ruby.rb

Line 51 in eac9b35

def _read_from_socket(nbytes)

Not raising exceptions and immediately rescuing will increase performance.

Linking: petergoldstein/dalli#756

[byroot]

Yeah I meant to use that since a while, I need to finish it: #926

[nateberkopec]

Cheers! Just noticed it today in production, glad it's already on your radar.

[byroot]

Done.