CBLT-283:  create CGI to display list of file in S3 bucket, for mobile

Change-Id: I4b82f3304b0b08875878943625b00713a4a3d0aa
Reviewed-on: http://review.couchbase.org/36998
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>