Use standard library context package

The package now requires Go 1.7 or higher.

.travis.yml

@@ -4,9 +4,6 @@ services:
   - redis-server
 
 go:
-  - 1.4
-  - 1.5.x
-  - 1.6.x
   - 1.7.x
   - 1.8.x
   - 1.9.x

redis/pool.go

@@ -16,6 +16,7 @@ package redis
 
 import (
 	"bytes"
+	"context"
 	"crypto/rand"
 	"crypto/sha1"
 	"errors"
@@ -26,7 +27,6 @@ import (
 	"time"
 
 	"github.com/garyburd/redigo/internal"
-	"golang.org/x/net/context"
 )
 
 var (

redis/pool_test.go

@@ -15,6 +15,7 @@
 package redis_test
 
 import (
+	"context"
 	"errors"
 	"io"
 	"reflect"
@@ -23,7 +24,6 @@ import (
 	"time"
 
 	"github.com/garyburd/redigo/redis"
-	"golang.org/x/net/context"
 )
 
 type poolTestConn struct {