monitoringplugin.py: Enhance verbose output function

- one space per verbose level at the begining
- optional prefix (for list output)
- output lists one item per line

monitoringplugin.py

@@ -357,9 +357,17 @@ class MonitoringPlugin(object):
 			return ''
 
 
-	def verbose(self, level, output):
+	def verbose(self, level, output, prefix=None):
 		if level <= self.options.verbose:
-			print 'V' + str(level) + ': ' + output
+			bol = 'V' + str(level) + ':' + ' ' * level
+			if prefix:
+				bol += '%s' % prefix
+			if type(output) in [str, unicode, ]:
+				print(bol + output)
+			elif type(output) in [list, ]:
+				print('\n'.join( ['%s%s' % (bol, l) for l in output] ) )
+			else:
+				print('%s%s' % (bol, output) )
 
 
 	def max_returncode(self, returncodes):