Client should validate the incoming host value

Convert host:port and URLs passed to client.New() into the proper
values, and return an error if the value is invalid.  Change CLI
to return an error if -master is invalid.  Remove Client.rawRequest
which was not in use, and fix the involved tests. Add NewOrDie

Preserves the behavior of the client to not auth when a non-https
URL is passed (although in the future this should be corrected).

test/integration/client_test.go

@@ -43,7 +43,7 @@ func TestClient(t *testing.T) {
 	storage, codec := m.API_v1beta1()
 	s := httptest.NewServer(apiserver.Handle(storage, codec, "/api/v1beta1/"))
 
-	client := client.New(s.URL, nil)
+	client := client.NewOrDie(s.URL, nil)
 
 	info, err := client.ServerVersion()
 	if err != nil {