Move "logger" package to under types, now that we have it.

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

derp/derp_client.go

@@ -15,7 +15,7 @@ import (
 
 	"golang.org/x/crypto/curve25519"
 	"golang.org/x/crypto/nacl/box"
-	"tailscale.com/logger"
+	"tailscale.com/types/logger"
 )
 
 type Client struct {

derp/derp_server.go

@@ -23,7 +23,7 @@ import (
 
 	"golang.org/x/crypto/curve25519"
 	"golang.org/x/crypto/nacl/box"
-	"tailscale.com/logger"
+	"tailscale.com/types/logger"
 )
 
 const magic = 0x44c55250 // "DERP" with a non-ASCII high-bit

derp/derphttp/derphttp_client.go

@@ -23,7 +23,7 @@ import (
 	"sync"
 
 	"tailscale.com/derp"
-	"tailscale.com/logger"
+	"tailscale.com/types/logger"
 )
 
 // Client is a DERP-over-HTTP client.