Do not require javascript-enabled clients

A simple submit-button is all that's required to make the branch selector
drop-down work on any client, so lets add one.

Noticed-by: Olivier Ramonat <olivier@ramonat.fr>
Signed-off-by: Lars Hjemli <hjemli@gmail.com>
diff --git a/cgit.css b/cgit.css
index 1e768b8..1b2e9d6 100644
--- a/cgit.css
+++ b/cgit.css
@@ -134,6 +134,18 @@
 	padding: 0px;
 }
 
+td#branch-dropdown-cell {
+	width: 99%;
+}
+
+input#switch-btn {
+	width: 20px;
+	border: solid 1px #aaa;
+	background-color: #bbb;
+	margin: 2px 0px 0px 0px;
+	padding: 0px;
+}
+
 div#sidebar div.infobox input.txt {
 	width: 100%;
 	border: solid 1px #aaa;