Add SSL Certificate expiration warnings

Adds status icons in data table and alert banners for
expiring and expired certificates.
Warning will be visible within 30 days of certificate
expiration.
Critical/danger indicators will be visible when certificate
is expired.

Signed-off-by: Yoshie Muranaka <yoshiemuranaka@gmail.com>
Change-Id: I6f8c27d4ba1563a79b46eec7b869366ecee42f75
diff --git a/src/store/modules/GlobalStore.js b/src/store/modules/GlobalStore.js
index dd12fc2..6511a45 100644
--- a/src/store/modules/GlobalStore.js
+++ b/src/store/modules/GlobalStore.js
@@ -25,7 +25,7 @@
   namespaced: true,
   state: {
     hostName: '--',
-    bmcTime: '--',
+    bmcTime: null,
     hostStatus: 'unreachable'
   },
   getters: {