Accessibility fixes:

	- changed buttons to spans since not being used in forms
	- added aria roles to html elements
	- changed low contrast colors

Change-Id: I56e784b226baa7f9b24346446a0a023fcea633d4
Signed-off-by: Michael Davis <michael.s.davis@ibm.com>
diff --git a/app/server-health/styles/sensors.scss b/app/server-health/styles/sensors.scss
index 7ee09cb..6152683 100644
--- a/app/server-health/styles/sensors.scss
+++ b/app/server-health/styles/sensors.scss
@@ -76,7 +76,7 @@
   .content-label {
     font-size: 1em;
     margin-left: .8em;
-    color: lighten($darkgrey, 10%);
+    color: $darkgrey;
   }
   .sensor__reading {
     @include fontCourierBold;