Cross-Platform Compatibility and Version Reporting

- Use `command -v` instead of `which` for better error trapping and control. On
Debian system it would show an error with `brew`, even though it was supposed to
check and ignore `brew` if it did not exist.
- Updated code that checked for "system" version of PHP, it now checks to for
PHP with `command -v` before processing the paths.
- Updated the code that sets the PHP version so that the proper version is
displayed after it has been configured.
- Removed a commented line of code, that was created when adding system PHP
checking.