Add the ability for Marketplace apps to upgrade from free to paid automatically

It would be beneficial for customers to have the ability to set an auto upgrade when installing an apps free trial.

At times, customers will heavily integrate the Atlassian Marketplace Application into their Atlassian Site. Once the free trial expires then application functionalities stop working which can cause internal problems for customers. Upgrading the app manually resolves this. However, this could be avoided if the customer has the ability to set an automatic upgrade.