[monitor]: monitor bootstrap doesn't fail if we can't connect to monitor URL

I see from time to time the error:

Traceback (most recent call last):
  File ".../bin/monitor.bootstrap", line 79, in <module>
    sys.exit(slapos.monitor.monitor.main())
  File ".../eggs/slapos.toolbox-0.92-py2.7.egg/slapos/monitor/monitor.py", line 379, in main
    sys.exit(monitor.bootstrapMonitor())
  File ".../eggs/slapos.toolbox-0.92-py2.7.egg/slapos/monitor/monitor.py", line 357, in bootstrapMonitor
    os.path.join(self.public_folder, 'feeds'))
  File ".../eggs/slapos.toolbox-0.92-py2.7.egg/slapos/monitor/monitor.py", line 296, in generateOpmlFile
    'title': self.getMonitorTitleFromUrl(feed_url + "/share/public/"),
  File ".../eggs/slapos.toolbox-0.92-py2.7.egg/slapos/monitor/monitor.py", line 215, in getMonitorTitleFromUrl
    response = urllib2.urlopen(url, context=context, timeout=timeout)
  File ".../parts/python2.7/lib/python2.7/urllib2.py", line 154, in urlopen
    return opener.open(url, data, timeout)
 [...]
ssl.SSLError: ('The read operation timed out',)```

This is usually when instance doesn't exist in frontend.

In order to prevent monitor bootstrap from failing, ignore all errors.