1. A system for creating or reconfiguring a virtual server image of a software application which is for deployment to a cloud of a particular hypervisor, comprising: a computer including a processor, memory and operating system; a memory space for use in creating virtual server images; an appliance configuration file that indicates configuration settings for use with the software application, including environment-variable settings that specify application data locations; an appliance builder which is used to generate or reconfigure a virtual server image, the virtual server image containing both the software application and a virtual machine capable of executing the software application in a particular hypervisor type, including performing the steps comprising receiving an indication as to the particular hypervisor type that will be used with the software application, reading the appliance configuration file to determine the configuration settings therein, writing, into the memory space, a bootable component of the virtual machine which is associated with the indicated particular hypervisor type, wherein different forms of bootable component are used for different hypervisor types, writing a non-bootable component of the virtual machine, together with the software application into the memory space, configuring the bootable component to load and execute the non-bootable component of the virtual machine in the memory space, and writing the memory space as the virtual server image which is for deployment to a cloud including the particular hypervisor; and a virtual server image updater, which receives a virtual server image patch to reconfigure the virtual server image from its original content to a reconfigured content, wherein the virtual server image updater is adapted to reconfigure the software application without modifying its application data and state.