Fix SRV record handling when target is shortname (#422)

* models/record.go: SRV targets are case insensitive. Downcase them.
* models/t_srv.go: Rename setTargetIntAndStrings() to setTargetSRVIntAndStrings() (makes it easier to search for /setTargetSRV/).
* pkg/js/parse_tests/021-srv.js*: SRV: Add parse_tests
* pkg/normalize/validate.go: SRV targets are hostnames, turn into FQDNs.
* Add  #rtype_variations warnings for future developers

pkg/js/parse_tests/021-srv.js

@@ -0,0 +1,7 @@
+D("foo.com","none"
+  , SRV('_ntp._udp', 1, 100, 123, 'one.foo.com.')
+  , SRV('_ntp._udp', 2, 100, 123, 'two')
+  , SRV('_ntp._udp', 3, 100, 123, 'localhost')
+  , SRV('_ntp._udp', 4, 100, 123, 'three.example.com.')
+  , SRV('_ntp._udp', 0, 0, 1, 'zeros')
+);

pkg/js/parse_tests/021-srv.json

@@ -0,0 +1,51 @@
+{
+  "dns_providers": [],
+  "domains": [
+    {
+      "dnsProviders": {},
+      "name": "foo.com",
+      "records": [
+        {
+          "name": "_ntp._udp",
+          "srvport": 123,
+          "srvpriority": 1,
+          "srvweight": 100,
+          "target": "one.foo.com.",
+          "type": "SRV"
+        },
+        {
+          "name": "_ntp._udp",
+          "srvport": 123,
+          "srvpriority": 2,
+          "srvweight": 100,
+          "target": "two",
+          "type": "SRV"
+        },
+        {
+          "name": "_ntp._udp",
+          "srvport": 123,
+          "srvpriority": 3,
+          "srvweight": 100,
+          "target": "localhost",
+          "type": "SRV"
+        },
+        {
+          "name": "_ntp._udp",
+          "srvport": 123,
+          "srvpriority": 4,
+          "srvweight": 100,
+          "target": "three.example.com.",
+          "type": "SRV"
+        },
+        {
+          "name": "_ntp._udp",
+          "srvport": 1,
+          "target": "zeros",
+          "type": "SRV"
+        }
+      ],
+      "registrar": "none"
+    }
+  ],
+  "registrars": []
+}