Change required version to Go 1.6

.travis.yml

@@ -1,9 +1,8 @@
 language: go
 go:
-  - 1.5.x
-  - 1.6.x
-  - 1.7.x
-  - 1.8.x
+  - 1.6
+  - 1.7
+  - 1.8
   - master
 
 before_install:

gogs.go

@@ -1,4 +1,4 @@
-// +build go1.5
+// +build go1.6
 
 // Copyright 2014 The Gogs Authors. All rights reserved.
 // Use of this source code is governed by a MIT-style