make failures thresholds configurable

contrib/yasnd.conf.example

@@ -1,4 +1,4 @@
-# hosts' list
+# *** Hosts' parameters ***
 host 10.0.0.1 {
 	hostname = "10.0.0.1"
 	lpt_pin = 2
@@ -13,6 +13,14 @@ host 10.0.0.254 {
 }
 # log verbosity: 0 - normal mode, 1 - verbose, 2 - most verbose
 debug = 2
+# *** Threshold parameters ***
+# Number of failures while hosts checking, that triggers SMS sending
+failures_first = 1
+# Number of failures while hosts checking, that triggers host's reset, if no reaction was received
+failures_second = 3
+# Number of failures while hosts checking, that clean host's failure statistics
+failures_third = 9
+# *** Notification parametes ***
 # Use LPT for reset target devices?
 # Note: first LPT pin is for management and it should not be used
 lpt_enable = true