create Native Ad Placement
Creates a new native ad placement. If the native ad placement of given name already exists, it will be returned.
Return
NativeAd placement instance, or null if the placement cannot be created.
Parameters
name
Unique name of placement. The same name will be used in addapptr.com account.
supports Main Image
True if the native ads returned should have main image asset. Keep in mind that if main image is used, it has to be displayed.