Port tests from SkyDNS

This adds *most* of the tests from SkyDNS, things lacking is
the stubzone checking, groups and the trim prefix. These
will be added in subsequent PRs and in separate test files.

middleware/etcd/setup_test.go

@@ -1,3 +1,5 @@
+// +build etcd
+
 package etcd
 
 // etcd needs to be running on http://127.0.0.1:2379