Clean up icons

Clean up duplicate svg icons from assets directory.
Created a statusIcon component to dynamically render
status icons instead of using background-image in
scss files.

- Moved/removed on, off, critical, warning svg icons from
  assets directory
- Updated background-image status icons to use <icon>
  or <status-icon> directive

Signed-off-by: Yoshie Muranaka <yoshiemuranaka@gmail.com>
Change-Id: Ic0f06d78b0861d6f60d40b2dcc0b80fd6dad2a88
diff --git a/app/common/styles/layout/header.scss b/app/common/styles/layout/header.scss
index 084fe71..5a7a9d1 100644
--- a/app/common/styles/layout/header.scss
+++ b/app/common/styles/layout/header.scss
@@ -149,6 +149,10 @@
       width: 1rem;
     }
 
+    .status-icon {
+      vertical-align: text-top;
+    }
+
     &:hover {
       background: $background-01;
     }