select2: use wider search field, better UI.

rhodecode/public/css/select2.less

@@ -154,8 +154,8 b' select.select2{height:28px;visibility:hi'
 }
 
 .select2-search input {
-    width: auto !important;
-    margin: .5em;
+    width: 100%;
+    margin: .5em 0;
     padding: .5em;
 }