Add code to remove newline in smtpclient.rb : invoke_auth

[joastbg]

Some username/password combinations will make a new line in the auth string, row 56 smtpclient.rb.

Simple fix:
str = ["\0#{@Args[:auth][:username]}\0#{psw}"].pack("m").chomp.gsub("\n","")

As it is now a error will come from some servers, because the newline in the auth-string:
501 Syntax error at character position 71. CR and LF must be CRLF paired. See RFC 2821 #2.7.1.

[tmm1]

Fixed in #364