MEDIUM: dns: Add resolve-opts "ignore-weight"

It was noted in #48 that there are times when a configuration
may use the server-template directive with SRV records and
simultaneously want to control weights using an agent-check or
through the runtime api.  This patch adds a new option
"ignore-weight" to the "resolve-opts" directive.

When specified, any weight indicated within an SRV record will
be ignored.  This is for both initial resolution and ongoing
resolution.
diff --git a/include/types/dns.h b/include/types/dns.h
index 5a60c07..8347e93 100644
--- a/include/types/dns.h
+++ b/include/types/dns.h
@@ -249,6 +249,7 @@
 	int pref_net_nb; /* The number of registered preferred networks. */
 	int accept_duplicate_ip; /* flag to indicate whether the associated object can use an IP address
 				    already set to an other object of the same group */
+	int ignore_weight; /* flag to indicate whether to ignore the weight within the record */
 };
 
 /* Resolution structure associated to single server and used to manage name