Only consider an option having proxy when both proxy host and port are set.

This patch is to fix the a bug in parseArguments() where proxy port never get set when 

                } else if (line.trim().startsWith("secret_key")) {
                    options.setAWSSecretKey(line.substring(line.indexOf("=") + 1).trim());
                } else if (!options.getHasProxy() && line.trim().startsWith("proxy_host")) {
                    options.setProxyHost(line.substring(line.indexOf("=") + 1).trim()); <==== getHasProxy() will return true after this line
                } else if (!options.getHasProxy() && line.trim().startsWith("proxy_port")){
                    options.setProxyPort(Integer.parseInt(line.substring(line.indexOf("=") + 1).trim()));
                }