Clean up headers

Updates headers to match style guide and makes them consistent
throughout pages in the GUI. Removes instances where a header
element existed and a different header style was being applied.
For example, <h2 class="h4">

Tested: Ran GUI locally and verified that headers look consistent
and have the appropriate sizing while using Chrome, Firefox and
Safari.

Change-Id: I187136298ed2bfd36c40c2b80d5a4f20947cbe56
Signed-off-by: beccabroek <beccabroek@gmail.com>
diff --git a/app/server-control/controllers/power-usage-controller.html b/app/server-control/controllers/power-usage-controller.html
index 3e7c63f..5369827 100644
--- a/app/server-control/controllers/power-usage-controller.html
+++ b/app/server-control/controllers/power-usage-controller.html
@@ -6,7 +6,7 @@
   <form class="power-usage__form" role="form" action="">
     <section class="row column">
       <div class="page-header">
-        <h2 class="bold h4">Power information</h2>
+        <h2 class="bold">Power information</h2>
       </div>
       <fieldset>
           <ul class="power-usage__metadata-wrapper">