App installers now terminate installation if the Multi-user app is already installed

Prior to this update, the light, silent, and full installers installed the Cornerstone Classroom app in %appdata%\Centra even if the app was already installed in C:\Program Files (x86)\SabaMeeting folder, thereby resulting in two separate instances of the app and causing subsequent problems with client launch and usage.

In this update, when users run either the light app installer or the silent app installer or the full app installer, the system checks if the Cornerstone Classroom Multi-user app (Admin app) is already installed on the system, and if so then it does not install the App again. In such a scenario, these installers display the following error message and exit the installation: "Cornerstone Classroom App is already installed on your system by your system administrator. Please uninstall before proceeding or contact your system administrator."

If the installer finds the standard (single user) installer, then it upgrades the installation as it did prior to this update.