Add option to toggle password fields

Change-Id: I07a16697d2cbf9215176995b1d65ecfcc1094141
diff --git a/dev/scss/base/icons.scss b/dev/scss/base/icons.scss
index 24ee8eb..0a0c109 100644
--- a/dev/scss/base/icons.scss
+++ b/dev/scss/base/icons.scss
@@ -36,3 +36,5 @@
 $fa-redo:         "\f01e";
 $fa-warn:         "\f071";
 $fa-token:        "\1f511";
+$fa-show:         "\1f441";
+$fa-hide:         "\f070";