use default timeout/retry settings

resolver does not update these if these weren't set, and does not look
at the spec's defaults. This change makes it at least use something as a
default (using spec's default has gone to ticket #518)

src/bin/resolver/resolver.cc

@@ -66,6 +66,8 @@ private:
 public:
     ResolverImpl() :
         config_session_(NULL),
+        timeout_(2000),
+        retries_(3),
         rec_query_(NULL)
     {}