Add "Apple System Profiler XML" with glob *.spx

Apples "system_profiler" can save information about the machine in XML format and uses the *.spx extension.

See e.g.
http://www.manpagez.com/man/8/system_profiler/osx-10.6.php
http://www.theinstructional.com/guides/a-closer-look-at-system-information

It uses a XML header as follows:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">