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/overview/controllers/system-overview-controller.html b/app/overview/controllers/system-overview-controller.html
index e555641..c3534da 100644
--- a/app/overview/controllers/system-overview-controller.html
+++ b/app/overview/controllers/system-overview-controller.html
@@ -106,7 +106,7 @@
 								</div>
 							</div>
 							<div class="column small-1 large-1">
-								<button class="accord-trigger"></button>
+								<span class="button accord-trigger"></span>
 							</div>
 						</div>
 					</div>