Add the ability to create zip files.

[lowks]

Add the ability to create zip archives somewhere along lines like this:

Radpath.files("/tmp", "log") |> Radpath.zip("myzip.zip")

or

Radpath.dirs("/tmp") |> Radpath.zip("myzip2.zip")

[lowks]

Currently this works but then there is still a problem where it includes the full parent path of a directory. Have to find out why this is and get rid of it.