Hide testing state by default to avoid perceptual diffs

The perceptual diff extension in Behat defaults to taking
a screenshot of every browser step, including the
"started testsession" one. A simple way to avoid this view
changing is hiding the variable state behind a click event.
The state info is mostly used for manual testing via
dev/tests/startsession anyway.

templates/Includes/TestSession_State.ss

@@ -1,10 +1,10 @@
 <% if State %>
 <p>
-	Current testing state
-<ul>
-	<% loop State %>
-	<li><strong>$Name:</strong> $Value</li>
-	<% end_loop %>
-</ul>
+	<a href="#" onclick="document.getElementById('state').style.display = 'block'; return false;">Show testing state</a>
+	<ul id="state" style="display: none;">
+		<% loop State %>
+		<li><strong>$Name:</strong> $Value</li>
+		<% end_loop %>
+	</ul>
 </p>
 <% end_if %>