Merge branch 'note-form-text-color' into 'master'

Fixes issue with note form inheriting text color

It was only really noticeable on dark themed diffs

![Screen_Shot_2016-04-20_at_14.44.58](/uploads/4f32b487de7e4c09a494dc3c8c767ece/Screen_Shot_2016-04-20_at_14.44.58.png)

See merge request !3834

app/assets/stylesheets/pages/note_form.scss

@@ -42,6 +42,7 @@
 .note-textarea {
   display: block;
   padding: 10px 0;
+  color: $gl-gray;
   font-family: $regular_font;
   border: 0;