1. A system for supporting patching in a multitenant application server environment, comprising: one or more computers, including an application server environment executing thereon, together with a plurality of deployable resources which can be used within the application server environment, one or more resource group templates, which define groupings of deployable resources within a domain, and one or more partitions, wherein each partition provides an administrative and runtime subdivision of the domain, and wherein the system can associate one or more partitions and resource group templates with a tenant, for use by the tenant; and wherein the system includes a patching feature that takes advantage of high availability features built into an application server environment to apply patches in a controlled manner that maintains a domain's ability to operate without interruption.