FTP monitor: add check_ftp option to hide FTP banner ouput

[zenoss]

FTP monitor need to be modified to use the '-j' option of check_ftp in order to hide the FTP banner output.
From check_ftp --help:

-j, --jail
    Hide output from TCP socket

Currently:

DEBUG:zen.zencommand:Command: '/bin/sh -c exec $ZENHOME/libexec/check_ftp -H 130.125.168.192.in-addr.arpa -p 21 -t 60 -r crit -M warn'
DEBUG:zen.zencommand:Output: 'FTP OK - 0.010 second response time on port 21 [220---------- Welcome to Pure-FTPd [TLS] ----------
220-You are user number 1 of 50 allowed.
220-Local time is now 16:12. Server port: 21.
220-IPv6 connections are also welcome on this server.
220 You will be disconnected after 15 minutes of inactivity.]|time=0.009627s;0.000000;0.000000;0.000000;60.000000'
DEBUG:zen.zencommand:Process check_ftp -H 130.125.168.192.in-addr.arpa -p 21 -t 60 -r crit -M warn  stopped (0), 0.138736 elapsed
DEBUG:zen.zencommand:The result of "$ZENHOME/libexec/check_ftp -H 130.125.168.192.in-addr.arpa --use-ipv4 -p 21 -t 60 -r crit -M warn" was "FTP OK - 0.010 second response time on port 21 [220---------- Welcome to Pure-FTPd [TLS] ----------"

should be:

Command: '/bin/sh -c exec $ZENHOME/libexec/check_ftp -H 130.125.168.192.in-addr.arpa -j -p 21 -t 60 -r crit -M warn'
DEBUG:zen.zencommand:Output: 'FTP OK - 0.011 second response time on port 21|time=0.010657s;0.000000;0.000000;0.000000;60.000000'
DEBUG:zen.zencommand:Process check_ftp -H 130.125.168.192.in-addr.arpa -j -p 21 -t 60 -r crit -M warn  stopped (0), 0.179539 elapsed
DEBUG:zen.zencommand:The result of "$ZENHOME/libexec/check_ftp -H 130.125.168.192.in-addr.arpa -j -p 21 -t 60 -r crit -M warn" was "FTP OK - 0.011 second response time on port 21|time=0.010657s;0.000000;0.000000;0.000000;60.000000"
DEBUG:zen.zencommand:storing time = 0.010657 in: Devices/130.125.168.192.in-addr.arpa/FtpMonitor_time