testing.T.Run was introduced in Go 1.7, not Go 1.8

Make tests that were locked on 1.8 to run on Go 1.7.

Fix ina219 tests to only compile on Go 1.7 since it uses testing.t.Run().

devices/cap1xxx/cap1xxx_go1_7_test.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
-// +build go1.8
+// +build go1.7
 
 package cap1xxx
 

experimental/devices/ina219/ina219_go1_7_test.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
+// +build go1.7
+
 package ina219
 
 import (

experimental/devices/nrzled/nrzled_go1_7_test.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
-// +build go1.8
+// +build go1.7
 
 package nrzled