revert ROENROLL-1815 outage banner

src/app/app.component.html

-<!--div class="alert-banner">
-  <p><md-icon class="material-icons error" role="img" aria-hidden="true">warning</md-icon> Course Search & Enroll will not be available from June 28 at 4:00pm to July 8 at 8:00am due to the <a href="https://upgrade.sis.wisc.edu/" target="_blank">SIS Upgrade.</a></p>
-</div-->
 <header ngClass.sm="hide-navigation-bar" ngClass.xs="hide-navigation-bar" role="banner">
   <cse-header></cse-header>
   <cse-navigation></cse-navigation>

src/app/app.component.scss

@@ -32,25 +32,3 @@ main {
   min-width: 360px;
   height: 100vh;
 }
-
-.alert-banner {
-  position: absolute;
-  top: 0;
-  width: 100%;
-  background-color: white;
-  p {
-    margin: 13px 0;
-    padding: 0px 15px;
-    font-family: mat-font-family($config);
-    font-size: 13px;
-    -webkit-font-smoothing: antialiased;
-  }
-  md-icon {
-    font-size: 16px;
-    color: #ff8000;
-    top: 2px;
-  }
-  a {
-    text-decoration: none;
-  }
-}