Compile issues on Ubuntu 16.04, golang 1.10.1

[rnicksic]

I ran into a couple of compile issues on Ubuntu 16.04, golang 1.10.1

Incorrect variable type in engine/vserver_test.go:972 - both values need to be %t instead of %s.
incorrect variable type in healthcheck/dns.go:143 - rc needs to be %d instead of %s.