Add `on_plugin_install.exe` to support run as admin
Add `on_plugin_install.exe` to support run as admin

Add `on_plugin_install.exe` to support running with elevated privileges.
__NB__ Running `on_plugin_install.bat` using elevated privileges does not
seem to be supported using the [`ShellExecuteEx`][1] function (even when
running through `cmd.exe`).

[1]: https://msdn.microsoft.com/en-us/library/windows/desktop/bb762154%28v=vs.85%29.aspx

wheeler-microfluidics/dmf_control_board_plugin