1. A method of virtualizing an application configured to be installed natively and executed on a plurality of operating systems, the method comprising: creating a plurality of input configuration files, each input configuration file corresponding to a different one of the plurality of operating systems, each input configuration file comprising a collection of configurations made to a computing device executing the corresponding operating system by native installation of the application on the computing device; combining the plurality of input configuration files into an application template, the application template comprising a plurality of conditional layers, each conditional layer corresponding to both a different one of a plurality of operating systems and the input configuration file that corresponds to the operating system that corresponds to the conditional layer, each conditional layer including the collection of configurations of the input configuration file that corresponds to the conditional layer; and providing the application template to a virtual application executable constructor operable by a user and configured to use the application template to build a virtualized application executable configured to execute on the plurality of operating systems without installation, the application executing within a virtual operating system when the virtualized application executable is executed on one of the plurality of operating systems, the virtualized application executable comprising the plurality of conditional layers, the plurality of conditional layers being readable by a virtualization runtime during initialization of the virtualized application executable on a particular one of the plurality of operating systems, the virtualization runtime being configured to identify the conditional layer corresponding to the particular operating system and use the collection of configurations of the identified conditional layer to configure the virtualized application, the virtualization runtime being further configured to ignore the collection of configurations of each of the plurality of conditional layers that does not correspond to the particular operating system.