Integrate libarchive (Archive::Extract::Libarchive) to support other archive types

[bricas]

We currently limit the site to .zip files (we've converted what was left in .rar and .arj format to .zip) and we use Archive::Zip to peek at and extract the data.

If we're going to handle user-submitted data, it would be nice to allow for other file formats.

Libarchive handles a number of formats, is fast and (as far as i can tell) reliable. The trick will just be getting it to compile on our server target and then coding our abstract class (SixteenColors::Archive) to use it.