Link directly to an app in the App Store app on the device. Determine the link to the app itself using the iTunes Link Maker at http://itunes.apple.com/linkmaker
From iOS 9 apple has adopted ATS(Application Transport Security) which is set of standards that paves way for secured communication and https is one of them.
You can bypass this adding the following key in iOS
Its in /private/etc/apache2 there you can find mime.types configuration file.
You can change after that restart the apache to take effect of your changes