v1.15: Add Get Products and Record Usage (recurring billing)

This release is very close to the one for our .NET library. To get a better understanding of the methods that were added and how they can be used, please check https://help.cryptolens.io/api/dotnet/articles/v4020.html.

Here are several examples of how the new methods can be used in Java:

Get Products

GetProductsResult getProducts = ProductMethods.GetProducts(APIKey.get("productmethods"));

if(!Helpers.IsSuccessful(getProducts)) {
    fail("Could not obtain a list of data objects.");
}

Record Usage

BasicResult res = Subscription.RecordUsage(APIKey.get("subscriptionmethods"),
        new RecordUsageModel(3349, "CMXKC-GUQRW-EJUGS-RRPUR", 1));

if(!Helpers.IsSuccessful(res)) {
    fail("Could not register usage");
}