CBQE-2445 add url check if it could connect to
download or open a web page.

Change-Id: Ibd301409303a50d04f2c797806b789136bd308c8
Reviewed-on: http://review.couchbase.org/42485
Reviewed-by: Thuan Nguyen <soccon@gmail.com>
Tested-by: Thuan Nguyen <soccon@gmail.com>