Construct an handler on a connected socket, optionally sending an initial
CRLF sequence will be sent to the host to trigger a login prompt (see
UnixLoginHandler.setSendInitialCRLF(boolean).
Construct an handler on the given input/output stream pair, optionally
sending an initial CRLF sequence will be sent to the host to trigger a
login prompt (see UnixLoginHandler.setSendInitialCRLF(boolean).