Fix mozilla#77 alert-info conflict

Author: pippinlee

demo/compiled/demo.css

@@ -120,8 +120,8 @@
 @alert-success-bg: @brand-primary;
 @alert-success-text: @white;
 
-@alert-info-bg: @lightyellow;
-@alert-info-text: @grey;
+@alert-info-bg: @blue;
+@alert-info-text: @white;
 
 @alert-warning-bg: @orange;
 @alert-warning-text: @white;