javascript_aggregator_clear_cache() should not recurse subdirectories

javascript_aggregator_clear_cache() calls file_scan_directory() with $recurse=TRUE, but it should be FALSE.

I had served js libraries commonly used sitewide at files/js/ .
After started using javascript_aggregator, one day I hit "clear the javascript cache." and boom! all my own js libraries got deleted!

As javascript_aggregator_cache() does not create any subdirectories, file_scan_directory() should be called with $recurse=FALSE.