Return unicode string in clipboard.readText(), fixes atom/atom#2145.

spec/api-clipboard-spec.coffee

@@ -0,0 +1,9 @@
+assert = require 'assert'
+clipboard = require 'clipboard'
+
+describe 'clipboard module', ->
+  describe 'clipboard.readText()', ->
+    it 'returns unicode string correctly', ->
+      text = '千江有水千江月，万里无云万里天'
+      clipboard.writeText text
+      assert.equal clipboard.readText(), text