Upgrade min Go version to 1.8

.travis.yml

@@ -2,7 +2,6 @@ language: go
 sudo: false
 
 go:
-  - 1.7.6
   - 1.8.3
   - tip
 
@@ -16,8 +15,6 @@ env:
 
 matrix:
   exclude:
-    - os: osx
-      go: 1.7.6
     - os: osx
       go: tip
     - os: linux

build.go

@@ -302,8 +302,8 @@ func (cs Constants) LDFlags() string {
 
 func main() {
 	ver := runtime.Version()
-	if strings.HasPrefix(ver, "go1") && ver < "go1.7" {
-		fmt.Fprintf(os.Stderr, "Go version %s detected, restic requires at least Go 1.7\n", ver)
+	if strings.HasPrefix(ver, "go1") && ver < "go1.8" {
+		fmt.Fprintf(os.Stderr, "Go version %s detected, restic requires at least Go 1.8\n", ver)
 		os.Exit(1)
 	}