Add windows detect_installer capability

Initial implementation is basic and does not contain excellent error
checking, but for any distribution of Windows and any architecture the
installer will be the same, so not really a hugely complicated effort.
Add windows run_install capability

This required the modification of the archive object behavior to deal
with the Windows installer, which is an MSI file, not a tarball.
Isolate archive unpacking logic in PEBuild::Unpack

This makes archive that much cleaner, and clearly isolates the logic for
determining what action to take to correctly deploy a given kind of
installer archive.
Add Windows Server 2003 support

Windows Server 2003 support wasn't added as I didn't originally have a
test machine or a need. After comments in Github and a few more spare
minutes it seemed like an easy win, so here it THEORETICALLY is. This is
not yet tested on a Windows Server 2003 machine, but it IS tested on
Windows Server 2008 (works great) and SHOULD also work on Server 2003.
Remove redundant logic in windows detect_installer

The stubs will probably never be used due to possible future API
changes, so no point having them. If they're ACTUALLY needed later it's
easy enough to build them out again.
Merge pull request #33 from reidmv/windows-support

Windows support