Update Client.pm to use a more portable version of \r\n

Based on perlport, Issues > Newlines

```
A common misconception in socket programming is that \n eq \012 everywhere. When using protocols such as common Internet protocols, \012 and \015 are called for specifically, and the values of the logical \n and \r (carriage return) are not reliable.
    print SOCKET "Hi there, client!\r\n";      # WRONG
    print SOCKET "Hi there, client!\015\012";  # RIGHT
```

the Socket package exports one $CRLF variable - not exported by default, you should pass :crlf export flag.

see perldoc Socket