Post-install script files can be named anything one desires, but the class within
the file must be the same name as the file with all path separators replaced by
underscores plus "_postinstall
".
In other words, this postinstall script:
Path/To/Script.php
must contain a class named Path_To_Script_postinstall Due to casing differences between operating systems, it is recommended to always use lowercased file names.