Rename spinner.gif to select2-spinner.gif to prevent collisions with very common filename.

select2.css

@@ -212,13 +212,13 @@ Version: @@ver@@ Timestamp: @@timestamp@@
 }
 
 .select2-search input.select2-active {
-    background: #fff url('spinner.gif') no-repeat 100%;
-    background: url('spinner.gif') no-repeat 100%, -webkit-gradient(linear, left bottom, left top, color-stop(0.85, white), color-stop(0.99, #eeeeee));
-    background: url('spinner.gif') no-repeat 100%, -webkit-linear-gradient(center bottom, white 85%, #eeeeee 99%);
-    background: url('spinner.gif') no-repeat 100%, -moz-linear-gradient(center bottom, white 85%, #eeeeee 99%);
-    background: url('spinner.gif') no-repeat 100%, -o-linear-gradient(bottom, white 85%, #eeeeee 99%);
-    background: url('spinner.gif') no-repeat 100%, -ms-linear-gradient(top, #ffffff 85%, #eeeeee 99%);
-    background: url('spinner.gif') no-repeat 100%, linear-gradient(top, #ffffff 85%, #eeeeee 99%);
+    background: #fff url('select2-select2-spinner.gif') no-repeat 100%;
+    background: url('select2-spinner.gif') no-repeat 100%, -webkit-gradient(linear, left bottom, left top, color-stop(0.85, white), color-stop(0.99, #eeeeee));
+    background: url('select2-spinner.gif') no-repeat 100%, -webkit-linear-gradient(center bottom, white 85%, #eeeeee 99%);
+    background: url('select2-spinner.gif') no-repeat 100%, -moz-linear-gradient(center bottom, white 85%, #eeeeee 99%);
+    background: url('select2-spinner.gif') no-repeat 100%, -o-linear-gradient(bottom, white 85%, #eeeeee 99%);
+    background: url('select2-spinner.gif') no-repeat 100%, -ms-linear-gradient(top, #ffffff 85%, #eeeeee 99%);
+    background: url('select2-spinner.gif') no-repeat 100%, linear-gradient(top, #ffffff 85%, #eeeeee 99%);
 }
 
 
@@ -337,7 +337,7 @@ disabled look for already selected choices in the results dropdown
 }
 
 .select2-more-results.select2-active {
-    background: #f4f4f4 url('spinner.gif') no-repeat 100%;
+    background: #f4f4f4 url('select2-spinner.gif') no-repeat 100%;
 }
 
 .select2-more-results {
@@ -424,7 +424,7 @@ disabled look for already selected choices in the results dropdown
 }
 
 .select2-container-multi .select2-choices .select2-search-field input.select2-active {
-    background: #fff url('spinner.gif') no-repeat 100% !important;
+    background: #fff url('select2-spinner.gif') no-repeat 100% !important;
 }
 
 .select2-default {